I read one review of this stunning film that wondered why it was called Gravity (the review was in the Guardian - and it was positive) since most of the movie's scenes are set where there is a lack of gravity.
And there's the rub. At the altitude the film is set, Earth's gravity is almost as strong as it is here on the surface. It's just that the spacecraft and all the other debris are travelling so fast horizontally that they permanently fall around the planet, apparently weightless. But the reviewer doesn't understand this and thinks he knows how it should be up there. Stuck as we are in an environment where everything falls down, most of us are like the reviewer in that we have little idea how things work in the highly newtonian realm of spaceflight.
Gravity does dominate up there and I'll bet Director Alfonso Cuarón knows it. He and the team behind this movie seem to have researched the details of space flight very well indeed. Their work has a reality that is utterly compelling and believable. The lighting and textures of the ships, their components and, most important, of Earth itself are as if taken directly from the reams of photography that has come to us from recent actual space travellers. Yet Cuarón has carefully bent the truth enough to allow his story to play out so that it probably requires a geek to be able to pick holes in the technicalities.
I'm often described as a space geek and I saw much that I could pick at - in the physics, procedures or storyline. But I didn't care and neither should anyone else. This vicarious trip into the glorious vacuum above Earth was a treat, a reminder of our puny selves in a great universe that does not need nor care about our presence. The film accurately portrayed the beauty of our home and the place it has near our Sun while pointing out that we only get to exist off the planet by our intelligence and wits. This could also be true for our species on the planet if we want to maintain our civilisation.
The movie's first shot is very, very long, and bravely so, displaying Cuarón's sensitivity to the IMAX format. In it, Clooney and Bullock sadly start out as an annoying double act. He is seen showboating around the Shuttle and Hubble in a jetpack with a carefree wisecracking one-dimensionality that was in complete contrast to the film's spatial and metaphorical depth. No astronaut would ever act in such a cavalier fashion. Bullock, meanwhile, sets a tone of a barely professional astronaut who, at the drop of a space wrench, turns into a panicking insult to the intelligence of womanhood.
I struggled to buy into Bullock's character until the second half. Her daughter's backstory gave some 2001-esque depth and emotion to an otherwise simpering little girl of a character who did not display much of the toughness and competence I would have expected from anyone in the US astronaut corp. Only towards the end did she show the kind of thoughtful pluck drilled into these hard-nosed technocrats.
The claustrophobic quality of the spacecraft interiors inhabited by Bullock sat in awesome contrast to the infinite exteriors rendered by Cuarón's special effects team. This is perfect material for the Imax 3D format. Such care had been taken with the details. So many nods to real events in space flight - interior fires, flooded capsules, crashing Soyuz. I nearly cheered when I recognised the constellations in view over the night-time Earth.
The re-entry scene was stunningly realised. I felt like I really was seeing hardware passing through air at 5 miles per second. It was the visual highlight of a visually stunning movie. As I left the cinema, I heard a guy behind me say to his friend, "That's what Imax 3D was made for." Amen, my friend.
Friday, 8 November 2013
Wednesday, 31 July 2013
Hybrid car - continuing impressions
It just so happened that my hybrid Yaris was bought at the same time as my son was attempting to climb all Scotland 282 Munros (mountains over 3,000 feet or 914 metres) in a single season. Consequentially, I've done a lot of driving around in support of his endeavour and this has given me a lot of experience with the car. Overall, I'm very much enjoying the car as I get to understand its characteristics. With all these miles around the country's Highlands, I tend to keep my fuel consumption between 65 and 70 miles per gallon.
Then we left for a three-week spell to cover his final push to the end of the challenge. During that time, I felt a change in the car's performance. Gradually, over the first week or so, the car felt a little more sluggish, as if something was holding it back. It seemed to need a little more power from the engine to get it going and was less keen to drop into fully electric mode at slow speeds. As a result, the battery discharged less often and, for the first time, I saw the battery display show it as being full.
The consumption figures reflected this change. Throughout the three weeks up north, the consumption stayed solidly around the 60mpg mark. I became increasingly certain that something within the car had changed. I was convinced that my driving techniques were very similar to what they had been before the trip, when I had been following my son along roads further south. The sense that something was holding the car back was a disappointment and I began to think of how I would approach the subject with the mechanics. "Hi, I think I've detected a 10 per cent drop in my car's performance. Can you run a battery of tests to confirm this?"
There are a lot of possible sources of increased friction and the obvious culprit was a soft tyre so I made a point of checking them. Nope. Perhaps one of the brakes was the problem but how do I check that? That or any problem with the car's traction system would have to await specialist work when I return. What made it worse for me was that the early part of the tip was during a heatwave when the atmospheric density was lower and therefore so was the drag, something that should have countered my perceived problem.
Then we made the long trip back.
Soon we had left the winding, undulating single-track roads of the far north and were back on 2-lane roads with a higher average speed. As I emptied the tank, I watched the mpg meter slowly increment to a better figure. Then after a top-up at Pitlochry, I found it easy to maintain 55mph at about 70 miles per gallon - that was as good as I was getting before the trip.
Since then, the car's performance has been exactly as I was used to prior to the trip - the meter is currently sitting at 71mpg as I tootle around town. My current hypothesis invokes a mixture of the stop-start driving that is constant feature of the single-track road with its passing places, the very steep undulating nature of the landscape and its roads, and a notion that the road surface preferred up north is maybe different to cope with the harsher winters and the need to provide more grip. I don't know, but I'm sure happy to see that the car is fine.
Then we left for a three-week spell to cover his final push to the end of the challenge. During that time, I felt a change in the car's performance. Gradually, over the first week or so, the car felt a little more sluggish, as if something was holding it back. It seemed to need a little more power from the engine to get it going and was less keen to drop into fully electric mode at slow speeds. As a result, the battery discharged less often and, for the first time, I saw the battery display show it as being full.
The consumption figures reflected this change. Throughout the three weeks up north, the consumption stayed solidly around the 60mpg mark. I became increasingly certain that something within the car had changed. I was convinced that my driving techniques were very similar to what they had been before the trip, when I had been following my son along roads further south. The sense that something was holding the car back was a disappointment and I began to think of how I would approach the subject with the mechanics. "Hi, I think I've detected a 10 per cent drop in my car's performance. Can you run a battery of tests to confirm this?"
There are a lot of possible sources of increased friction and the obvious culprit was a soft tyre so I made a point of checking them. Nope. Perhaps one of the brakes was the problem but how do I check that? That or any problem with the car's traction system would have to await specialist work when I return. What made it worse for me was that the early part of the tip was during a heatwave when the atmospheric density was lower and therefore so was the drag, something that should have countered my perceived problem.
Then we made the long trip back.
Soon we had left the winding, undulating single-track roads of the far north and were back on 2-lane roads with a higher average speed. As I emptied the tank, I watched the mpg meter slowly increment to a better figure. Then after a top-up at Pitlochry, I found it easy to maintain 55mph at about 70 miles per gallon - that was as good as I was getting before the trip.
Since then, the car's performance has been exactly as I was used to prior to the trip - the meter is currently sitting at 71mpg as I tootle around town. My current hypothesis invokes a mixture of the stop-start driving that is constant feature of the single-track road with its passing places, the very steep undulating nature of the landscape and its roads, and a notion that the road surface preferred up north is maybe different to cope with the harsher winters and the need to provide more grip. I don't know, but I'm sure happy to see that the car is fine.
Wednesday, 12 June 2013
Hybrid car - initial impressions
Those who know me know that I like to explore technology; like computers, synthesisers, cameras, video, GPS, aircraft, spacecraft, and so on. Unsurprisingly, even cars do not escape my interest but not in the usual petrolhead manner. Unlike just about all men I meet, my interest is not in raw power or seat-bending acceleration. I like to see efficiency. I'm an eco'miser' and love it when I get high figures for a vehicle's consumption (in miles per gallon).
Ever since I got my first car in 1983, I've kept a careful note of how many miles I drive and how much fuel goes into the car. This quickly settled into a particular methodology in order to try and gain consistent results that would be more of a measure of the car's actual efficiency and less of an indicator of my poor measurement techniques. Therefore, every time I go to a petrol station to fill up, I always do so to the point where the pump stops the delivery automatically. I then restart filling and if it stops soon after, that is a reasonable confirmation that the tank is full. Sometimes the pump does stop prematurely but I tend to know when this has occurred because I'm usually aware of how much should be going into the tank. An additional part of the routine for many years was that I would then dribble in a bit more to round the money up to the next 10 pence. However, the high cost of fuel has made this impossible to achieve accurately and I've given up on that. I do accept that all this is probably an example of mild obsessive/compulsive behaviour but I don't worry about that.
Next I take a note of the car's odometer. Until the advent of the computer spreadsheet, this figure and that for the fuel would be entered into a notebook so that once I got hold of a calculator, I could work out the MPG figure. Since I knew how many miles I'd done since the last fill, and how much fuel had been required to restore a full tank, then a simple division would yield a figure for consumption - as soon as I had converted litres to gallons. I still have the accurate conversion factor in my head - 0.219975!
This constant measurement of consumption does tend to teach one a little about the efficiency of cars. I've seen how winter driving is a lot less efficient than summer driving. This is for a host of reasons - some obvious. Headlights and fans are power-hungry and they get it from the generator which slows down the engine more when a heavy load of electricity demand has to be delivered. A less obvious reason for poor consumption in winter is the fact that cold air is significantly more dense than warm air, a detail that every aircraft pilot knows. At standard temperature and pressure, a cubic metre of air has a mass of about 1.25 kilograms. That's a lot of mass that has to be shoved aside when hammering down the motorway which is why driving at 70 mph is significantly more expensive than driving at 50. Further, that air is roughly 8 per cent more dense at zero Celsius when compared to 20C.
Then there is driving style. Every touch of the brakes means lost momentum, which had to be paid for in petrol in the first place so anticipation pays. When the accelerator pedal is depressed, extra fuel is squirted in to make the car respond. This means that if you drive by constantly raising and lowering your foot on the gas, it will cost you more than keeping your foot as static as possible. All the running gear in the car itself; wheel bearings, driveshaft CV joints, transmission gears and bearings and the engine's rotating parts; all combine to add friction that soaks up power. The engine especially has losses due to the fact that has to keep compressing volumes of air and I was trained to use this as 'engine braking' when coming to a stop.
You can take the engine out of the friction equation by going into neutral and coasting but this is frowned upon by the authorities. I've heard that if you're in an accident and you are found to have been in neutral, you are immediately deemed to be at fault - whatever happened, as you were clearly not in control of your car. I think that's patronising rubbish and I really don't understand why cars don't have a freewheel arrangement like pushbikes do. If the car is happy to roll downhill without spending more petrol, why not let it without draining its momentum with engine braking. Therefore, I have to admit, I occasionally let the car coast when conditions allow and I see substantial savings from it. What is totally nuts is the habit of some folks in the US (so-called hyper-milers) to switch off their engines completely when coasting. Modern cars often depend on the hydraulic pressure supplied by the engine for their braking and steering. Shudder!
In 2003, after many years of sharing an automatic car (rare in the UK, even now) with my wife, I bought my own car and went for a manual transmission so that my sons could learn to drive in it. I was immediately drawn to the Yaris because it had good consumption figures for the time and Toyota has a good reputation for reliability. This was a great arrangement because I was the only one driving it and therefore the only person to affect the consumption figures. What was even better was that although it was a low-end car, it came with a built in consumption meter. No longer would I have to wait to find out how my driving affected consumption. I was able to see the effects of changing styles and conditions almost in real time. This allowed me to refine my driving from an efficiency point of view - keep speed and therefore drag down, accelerate slowly, anticipate stops to limit the use of brakes and, yes, there was the occasional bit of coasting - engine running of course. In particular, I saw how driving around town is a killer for good petrol consumption. The internal combustion engine - never a terribly efficient machine for energy conversion - is just awful at dealing with the demands of stop/start driving.
I've had four conventional Yarises. (Or is the plural 'Yarii'?) All cars had 1 litre, 3-cylinder VVTi engines and all were manually geared. Here are samples of typical, not peak, actual summer consumption figures from them:
Yaris 1 (2004) - 50.16 mpg
Yaris 2 (2008) - 53.78 mpg
Yaris 3 (2010) - 58.27 mpg
Yaris 4 (2012) - 59.89 mpg
You may at first glance think that this demonstrates the gradual improvement in efficiency from the manufacturer, especially given that in 2009, Toyota made an effort to get the car's emissions down and reduce its road tax cost. But it so happens that Yaris 4 was older than 3 and was built before they uprated the range. When I first got it as a replacement after No.3 was written off, I immediately noticed that it was a very efficient car even though it was the same spec as Yaris 2, perhaps an indication that there are great variations between individual cars.
Also of note is that I found the consumption meter of the first Yaris gave readings that were only slightly more optimistic than mine - about 2 or 3 per cent high. The later ones were consistently 7 to 12 per cent high.
All this time, I had an eye on Toyota's hybrid offerings; the Prius, the hybrid Auris and now the hybrid Yaris. The big advantage of the hybrid system is that the stop/start part of driving is dealt with by an electric motor and battery to leave the internal combustion engine to supply power directly to the wheels only at speed, thereby allowing it to work at its most efficient rotation speed. All the power does ultimately comes from the engine because it also charges up the battery for use when going slow, as does the car's momentum, which is converted back to electricity to recharge the battery when slowing or braking. With careful use, the brake pads ought to last a very long time.
The Prius seemed to me to be a horribly large car for something that was meant to be efficient. Certainly too large for my needs. The Auris wasn't much better but when Toyota squeezed the hybrid system into a Yaris with a claimed combined consumption figure of 80.71 mpg, I became very interested and in May 2013, jumped at an ex-demo that became available. I thought to myself that with my frugal driving style, I've always been able to match or beat the manufacturer's combined consumption figures. Perhaps I can repeat it with the hybrid Yaris. This should be interesting.
I've refilled the tank five times since my starting fill-up and am getting a feel for its real-world performance, though my driving over some of that being far from typical. I've been making a lot of long journeys up north so much mileage has been done at 55 to 60 mph. Nevertheless, its been interesting. Here's the results:
228 miles - 16.68 litres - 62.14 mpg (64.9 on the meter, 4.4% optimistic)
358 miles - 23.95 litres - 67.95 mpg (61.5 on the meter, 9.5% pessimistic)
391 miles - 31.24 litres - 56.90 mpg (65.7 on the meter, 15.5% optimistic)
474 miles - 31.99 litres - 67.36 mpg (70.2 on the meter, 4.22% optimistic)
466 miles - 32.57 litres - 65.04 mpg (67.4 on the meter, 3.63% optimistic)
The pessimistic reading is obviously due to me failing to fill the tank to my normal point. This is shown by the apparently good second figure being balanced by the relatively poor third one. I'll know to take more care when filling up to get a consistent full indication.
So they are hardly figures to set the world alight - a slight improvement over the manual cars, but let's look deeper. As I mentioned, a lot of this driving was at speed on roads in the Highlands of Scotland. In this mode, the car is basically running as a 1.5-litre internal combustion engine driving a small, 1.2-tonne car through the air with the normal amount of drag to be expected. Only a little of the driving was in town with a few trips to work. In that mode, much of the stopping and starting is handled by the electric drive. The engine only runs either to maintain the amount of charge in the specialised battery or to provide drive once an appropriate speed has been reached or a large amount of power has been demanded.
After my third fill-up, I drove home - mostly uphill and the meter showed 60 mpg. Then the next morning, I drove to work and although it is mostly downhill, it was very slow traffic, the kind that drinks petrol for little gain. It took me 35 minutes to go 7 miles. Yet by the time I got parked, the meter was a shade under 80 mpg! Now that's where this little car gains! City stop-and-start motion with low aerodynamic drag is where it's really comfortable. I then drove up to the Highlands and back, holding a solid 56 mph for most of the time. All the way, I was able to keep the meter above 70 mpg right to the fourth refill. It does seem to show that I'm getting the measure of the vehicle; that I'm learning its ways and can finesse it into delivering a better result.
I think a lot more is still to be learned about how this car works in terms of getting the best efficiency out of it, but the main thing I'm noticing is that the MPG meter changes in ways that are very counter-intuitive to someone who finessed a manual car into its most efficient range. It is very odd when the stop-and-start of the traffic lights does not cause the consumption figure to tumble. In fact, traffic jams are an opportunity to gain on the meter as the car goes for miles, crawling along on electric power alone, using not a drop of petrol.
So what do I think of it so far? I love it!
For a small car (and remember that I'm used to the most basic models and equipment in the range), this is a very refined machine. I've driven many 'automatic' cars with various gearbox technologies and this is not only the most efficient of them all, it is by far the smoothest, quietest car I've ran. When you stop at the lights, it's completely silent. When you pull away, it glides up to speed with zero fuss. It's relaxing, gentle and well balanced. As speed is gained, the engine starts to supplement the power and recharge the battery, but above the road noise, its difficult to discern when this happens. The clever planetary gear arrangement is beautifully controlled to look after the routing of the power as needed, whether it's the electric motor driving the wheels, the engine doing so, the engine turning the motor to generate electricity to charge the battery, or the motor turning the engine to get it started. All very clever and very refined.
The regenerative concept is great. As you slow down or brake, a little of your momentum is being used to turn the electric motor thereby using it as a generator which recharges the battery. If you're coming down a steep hill (as I was after I left the Cairngorm Ski Centre), you can shift the gearstick down a notch to its 'B' position and gain what feels like low-gear engine braking which generates even more power for the battery. There is also a Neutral position during which the car does feel very eager to keep moving under its momentum (i.e. it's very frictionless), but in that mode, you're not recharging the battery.
Add on top of that that the car has lots of fancy knobs and whistles that I'm not used to. I've never had air-con and now I have dual-zone automatic air-con. I have a fancy touch-controlled audio system that also lets me monitor the car's efficiency in a nice graphic way. There's a USB socket, Aux socket, CD, FM & AM radio, and bluetooth capability. And there's a rear-view camera for reversing into tight spaces. Very nice. I don't need most of these and would happily have had a hybrid-drive car with basic equipment but I'm enjoying having these toys, given that they come with the beast.
Although the initial figures have been disappointing, I'm starting to see that it can deliver its promised efficiencies, given fewer long-haul drives. It is very much a town car and I'm looking forward to many commutes in it.
Ever since I got my first car in 1983, I've kept a careful note of how many miles I drive and how much fuel goes into the car. This quickly settled into a particular methodology in order to try and gain consistent results that would be more of a measure of the car's actual efficiency and less of an indicator of my poor measurement techniques. Therefore, every time I go to a petrol station to fill up, I always do so to the point where the pump stops the delivery automatically. I then restart filling and if it stops soon after, that is a reasonable confirmation that the tank is full. Sometimes the pump does stop prematurely but I tend to know when this has occurred because I'm usually aware of how much should be going into the tank. An additional part of the routine for many years was that I would then dribble in a bit more to round the money up to the next 10 pence. However, the high cost of fuel has made this impossible to achieve accurately and I've given up on that. I do accept that all this is probably an example of mild obsessive/compulsive behaviour but I don't worry about that.
Next I take a note of the car's odometer. Until the advent of the computer spreadsheet, this figure and that for the fuel would be entered into a notebook so that once I got hold of a calculator, I could work out the MPG figure. Since I knew how many miles I'd done since the last fill, and how much fuel had been required to restore a full tank, then a simple division would yield a figure for consumption - as soon as I had converted litres to gallons. I still have the accurate conversion factor in my head - 0.219975!
This constant measurement of consumption does tend to teach one a little about the efficiency of cars. I've seen how winter driving is a lot less efficient than summer driving. This is for a host of reasons - some obvious. Headlights and fans are power-hungry and they get it from the generator which slows down the engine more when a heavy load of electricity demand has to be delivered. A less obvious reason for poor consumption in winter is the fact that cold air is significantly more dense than warm air, a detail that every aircraft pilot knows. At standard temperature and pressure, a cubic metre of air has a mass of about 1.25 kilograms. That's a lot of mass that has to be shoved aside when hammering down the motorway which is why driving at 70 mph is significantly more expensive than driving at 50. Further, that air is roughly 8 per cent more dense at zero Celsius when compared to 20C.
Then there is driving style. Every touch of the brakes means lost momentum, which had to be paid for in petrol in the first place so anticipation pays. When the accelerator pedal is depressed, extra fuel is squirted in to make the car respond. This means that if you drive by constantly raising and lowering your foot on the gas, it will cost you more than keeping your foot as static as possible. All the running gear in the car itself; wheel bearings, driveshaft CV joints, transmission gears and bearings and the engine's rotating parts; all combine to add friction that soaks up power. The engine especially has losses due to the fact that has to keep compressing volumes of air and I was trained to use this as 'engine braking' when coming to a stop.
You can take the engine out of the friction equation by going into neutral and coasting but this is frowned upon by the authorities. I've heard that if you're in an accident and you are found to have been in neutral, you are immediately deemed to be at fault - whatever happened, as you were clearly not in control of your car. I think that's patronising rubbish and I really don't understand why cars don't have a freewheel arrangement like pushbikes do. If the car is happy to roll downhill without spending more petrol, why not let it without draining its momentum with engine braking. Therefore, I have to admit, I occasionally let the car coast when conditions allow and I see substantial savings from it. What is totally nuts is the habit of some folks in the US (so-called hyper-milers) to switch off their engines completely when coasting. Modern cars often depend on the hydraulic pressure supplied by the engine for their braking and steering. Shudder!
In 2003, after many years of sharing an automatic car (rare in the UK, even now) with my wife, I bought my own car and went for a manual transmission so that my sons could learn to drive in it. I was immediately drawn to the Yaris because it had good consumption figures for the time and Toyota has a good reputation for reliability. This was a great arrangement because I was the only one driving it and therefore the only person to affect the consumption figures. What was even better was that although it was a low-end car, it came with a built in consumption meter. No longer would I have to wait to find out how my driving affected consumption. I was able to see the effects of changing styles and conditions almost in real time. This allowed me to refine my driving from an efficiency point of view - keep speed and therefore drag down, accelerate slowly, anticipate stops to limit the use of brakes and, yes, there was the occasional bit of coasting - engine running of course. In particular, I saw how driving around town is a killer for good petrol consumption. The internal combustion engine - never a terribly efficient machine for energy conversion - is just awful at dealing with the demands of stop/start driving.
I've had four conventional Yarises. (Or is the plural 'Yarii'?) All cars had 1 litre, 3-cylinder VVTi engines and all were manually geared. Here are samples of typical, not peak, actual summer consumption figures from them:
Yaris 1 (2004) - 50.16 mpg
Yaris 2 (2008) - 53.78 mpg
Yaris 3 (2010) - 58.27 mpg
Yaris 4 (2012) - 59.89 mpg
You may at first glance think that this demonstrates the gradual improvement in efficiency from the manufacturer, especially given that in 2009, Toyota made an effort to get the car's emissions down and reduce its road tax cost. But it so happens that Yaris 4 was older than 3 and was built before they uprated the range. When I first got it as a replacement after No.3 was written off, I immediately noticed that it was a very efficient car even though it was the same spec as Yaris 2, perhaps an indication that there are great variations between individual cars.
Also of note is that I found the consumption meter of the first Yaris gave readings that were only slightly more optimistic than mine - about 2 or 3 per cent high. The later ones were consistently 7 to 12 per cent high.
All this time, I had an eye on Toyota's hybrid offerings; the Prius, the hybrid Auris and now the hybrid Yaris. The big advantage of the hybrid system is that the stop/start part of driving is dealt with by an electric motor and battery to leave the internal combustion engine to supply power directly to the wheels only at speed, thereby allowing it to work at its most efficient rotation speed. All the power does ultimately comes from the engine because it also charges up the battery for use when going slow, as does the car's momentum, which is converted back to electricity to recharge the battery when slowing or braking. With careful use, the brake pads ought to last a very long time.
The Prius seemed to me to be a horribly large car for something that was meant to be efficient. Certainly too large for my needs. The Auris wasn't much better but when Toyota squeezed the hybrid system into a Yaris with a claimed combined consumption figure of 80.71 mpg, I became very interested and in May 2013, jumped at an ex-demo that became available. I thought to myself that with my frugal driving style, I've always been able to match or beat the manufacturer's combined consumption figures. Perhaps I can repeat it with the hybrid Yaris. This should be interesting.
I've refilled the tank five times since my starting fill-up and am getting a feel for its real-world performance, though my driving over some of that being far from typical. I've been making a lot of long journeys up north so much mileage has been done at 55 to 60 mph. Nevertheless, its been interesting. Here's the results:
228 miles - 16.68 litres - 62.14 mpg (64.9 on the meter, 4.4% optimistic)
358 miles - 23.95 litres - 67.95 mpg (61.5 on the meter, 9.5% pessimistic)
391 miles - 31.24 litres - 56.90 mpg (65.7 on the meter, 15.5% optimistic)
474 miles - 31.99 litres - 67.36 mpg (70.2 on the meter, 4.22% optimistic)
466 miles - 32.57 litres - 65.04 mpg (67.4 on the meter, 3.63% optimistic)
The pessimistic reading is obviously due to me failing to fill the tank to my normal point. This is shown by the apparently good second figure being balanced by the relatively poor third one. I'll know to take more care when filling up to get a consistent full indication.
So they are hardly figures to set the world alight - a slight improvement over the manual cars, but let's look deeper. As I mentioned, a lot of this driving was at speed on roads in the Highlands of Scotland. In this mode, the car is basically running as a 1.5-litre internal combustion engine driving a small, 1.2-tonne car through the air with the normal amount of drag to be expected. Only a little of the driving was in town with a few trips to work. In that mode, much of the stopping and starting is handled by the electric drive. The engine only runs either to maintain the amount of charge in the specialised battery or to provide drive once an appropriate speed has been reached or a large amount of power has been demanded.
After my third fill-up, I drove home - mostly uphill and the meter showed 60 mpg. Then the next morning, I drove to work and although it is mostly downhill, it was very slow traffic, the kind that drinks petrol for little gain. It took me 35 minutes to go 7 miles. Yet by the time I got parked, the meter was a shade under 80 mpg! Now that's where this little car gains! City stop-and-start motion with low aerodynamic drag is where it's really comfortable. I then drove up to the Highlands and back, holding a solid 56 mph for most of the time. All the way, I was able to keep the meter above 70 mpg right to the fourth refill. It does seem to show that I'm getting the measure of the vehicle; that I'm learning its ways and can finesse it into delivering a better result.
I think a lot more is still to be learned about how this car works in terms of getting the best efficiency out of it, but the main thing I'm noticing is that the MPG meter changes in ways that are very counter-intuitive to someone who finessed a manual car into its most efficient range. It is very odd when the stop-and-start of the traffic lights does not cause the consumption figure to tumble. In fact, traffic jams are an opportunity to gain on the meter as the car goes for miles, crawling along on electric power alone, using not a drop of petrol.
So what do I think of it so far? I love it!
For a small car (and remember that I'm used to the most basic models and equipment in the range), this is a very refined machine. I've driven many 'automatic' cars with various gearbox technologies and this is not only the most efficient of them all, it is by far the smoothest, quietest car I've ran. When you stop at the lights, it's completely silent. When you pull away, it glides up to speed with zero fuss. It's relaxing, gentle and well balanced. As speed is gained, the engine starts to supplement the power and recharge the battery, but above the road noise, its difficult to discern when this happens. The clever planetary gear arrangement is beautifully controlled to look after the routing of the power as needed, whether it's the electric motor driving the wheels, the engine doing so, the engine turning the motor to generate electricity to charge the battery, or the motor turning the engine to get it started. All very clever and very refined.
The regenerative concept is great. As you slow down or brake, a little of your momentum is being used to turn the electric motor thereby using it as a generator which recharges the battery. If you're coming down a steep hill (as I was after I left the Cairngorm Ski Centre), you can shift the gearstick down a notch to its 'B' position and gain what feels like low-gear engine braking which generates even more power for the battery. There is also a Neutral position during which the car does feel very eager to keep moving under its momentum (i.e. it's very frictionless), but in that mode, you're not recharging the battery.
Add on top of that that the car has lots of fancy knobs and whistles that I'm not used to. I've never had air-con and now I have dual-zone automatic air-con. I have a fancy touch-controlled audio system that also lets me monitor the car's efficiency in a nice graphic way. There's a USB socket, Aux socket, CD, FM & AM radio, and bluetooth capability. And there's a rear-view camera for reversing into tight spaces. Very nice. I don't need most of these and would happily have had a hybrid-drive car with basic equipment but I'm enjoying having these toys, given that they come with the beast.
Although the initial figures have been disappointing, I'm starting to see that it can deliver its promised efficiencies, given fewer long-haul drives. It is very much a town car and I'm looking forward to many commutes in it.
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