Hybrid concept car achieves record fuel economy
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Volkswagen has built a concept diesel-electric hybrid that achieves a fuel economy of 313 miles per gallon, a record for such vehicles.
Unveiled at the Qatar motor show this week, the XL1 has actually been in development for around 10 years and could go into low-volume production, according to Angus Fitton, product affairs manager at Volkswagen.
‘The concept has evolved, so it’s a mixture of making clean-sheet design and setting out to make the car as efficient as possible,’ he told The Engineer.
Indeed, back in 2002 Volkswagen released the rather spartan ‘VW one-litre’ concept which used a single-cylinder 8.5bhp diesel engine to achieve a fuel economy milestone of one litre per 100km (or 285mpg).
‘In many ways it was a crude vehicle to drive, but it did demonstrate that if you took vehicle efficiency to extremes, this is what you could achieve. Many of the lessons learnt in that car made it into, for example, Bluemotion models.’
The concept was taken further in 2009 with the quicker and more practical ‘VW L1’, which had a two-cylinder TDI diesel hybrid engine – although fuel economy dropped to 189mpg.
Now, the XL1 hybrid combines practicality with a fuel economy of 313mpg (0.9 litres per 100km) and a CO2 emissions value of 24g/km.
The car can be driven for 22 miles (35km) on its 27bhp electric motor before the 48bhp diesel engine takes over. The battery is charged from a conventional household electric outlet, although it can also be regenerated through energy recovery from braking.
Streamlining and weight were also major considerations – the body was constructed from carbon-fibre-reinforced polymer parts (CFRP) using a unique process called advanced Resin Transfer Moulding (aRTM), developed and patented by Volkswagen. The teardrop-shaped monoque achieves drag coefficient of Cd 0.186.
‘Every element of the car is designed to be highly efficient, from the chassis, to the aerodynamics, to the engine, everything has been designed to reduce loading on the engine and to therefore maximise economy and lower emissions,’ said Fitton.
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Readers' comments (12)
Randy Kramer | 26 Jan 2011 6:16 pm
How was the MPG figure calculated? More specifically, was the first 22 miles (on battery powered) figured into the calculation? It would be much more meaningful if it were not--I'd like to know how much efficiency is built into the car / diesel engine, and not how much is faked by using a different source of energy.
Figures like these are like giving us one equation with two unknowns. If the MPG figure includes the first 22 miles, what was the average trip? I can imagine doing the calculation based on no trips exceeding 22 miles and coming up with an infinite MPG figure.
Another way to get a proper (imho) figure would be to start all trips with zero charge on the battery. (Presumably the diesel engine also recharges the battery.)
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Anonymous | 27 Jan 2011 9:29 am
Very impressive.
Regarding tacking into account the battery for the MPG calculations, I would expect so. The car has two engines, and two energy reservoirs. The reasonable thing is to start the test with both full, and proceed until both are completely empty.
Now, the problem is with the "miles per gallon" figure itself. Gallon of what? It doesn't make much sense for hybrids or electric vehicles. Hell, it doesn't make much sense when comparing diesel with gas engines, either.
You know what would make sense? Miles per Kilowatt. Or Watts per Kilometer. And to factor prices in, Miles per pound of both the electric and diesel engines, alone and in combination.
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Jonathan Douglas | 28 Jan 2011 12:53 pm
It would be miles per joule or kilojoule, or joules per kilometer.
The mpg figure should be quoted assuming the battery charge at the end of the test is the same as at the start, and also state the distance which can be driven on a full charge.
These figures are impressive but it should not come as too big a surprise. Good hybridisation with good recovery of energy from brakes etc. together with optimum driving style should be able to more than halve the typical consumption of any modern car.
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Peter Fox | 28 Jan 2011 12:57 pm
It seems to me if everybody sold their fossil fueled cars and bought electric would we have enough power stations.
Why can we not work with solar powered cars?
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Jon Knox | 28 Jan 2011 1:59 pm
I would like to know who, or rather which company the electric motor drive comes from?
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Steve | 28 Jan 2011 2:40 pm
I have been driving a hybrid car since 2002. The economy of my cars has proved very dependent on driving style just as with most cars. The experts say the hybrid offers the best savings on short runs. That may be so in theory. In practice a run to the supermarket in my present Honda Civic Hybrid records about 43 mpg whereas a drive of a 100 m to Cumbria will give 50 mpg. Setting the cruise control at 70mph on the motorway will give about 55 mpg. My previous Honda Insight, a two seater coupe, recorded 66.6 mpg over 65,000 miles. It too gave lower figures on short town journeys and better, up to 88 mpg, on longer ones. The journey to Cumbria almost always returned 72 mpg for the 105 m. I found that allowing the car to freewheel as much as possible was the best driving technique for low fuel consumption.
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James Stewart | 28 Jan 2011 7:55 pm
Actually the only valid comparison model between cars would be the cost per 1000 Km (or 1000 miles if you insist) driven. this includes the PLC estimate, the cost of the vehicle, cost of maintenance, and cost of fuel(s). Now if for example, Volkswagen could state $0.015/km compated to Honda's $0.05/km (these are arbitrary, made up figures), then they would have a strong sales point.
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Chris Creasey | 29 Jan 2011 10:28 am
I'm also suspicious that the MPG figures might be at say 40mph and that it might not be practical for safety and maneouverability. If VW are so good at this why didn't they enter (and win) the automotive X prize (www.progressiveautoxprize.org) with $10,000,000 of prize money? OK that money to VW might be loose change but there was a lot of publicity too and the results we independently verified at the Argonne national labs with tests for braking, acceleration, collision avoidance, range, speed etc.
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Ted | 31 Jan 2011 11:00 pm
I had Geo Metro Two Door and averaged 43-45mpg combined Hwy-City. I tracked the mileage and fuel for over a year. No its not as nice as the newer Hybrids but I aways wondered what a 1L turbo Diesel would do in one.
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Anonymous | 3 Feb 2011 11:31 am
As we stand today, with no real credibility in anything other than pouring a hydrocarbon into the vehicle, mpg is the realistic way of judging improvements. Eventually, low-carbon electricity and an order of magnitude improvement in battery capabilities may MAY make electric cars more common and give them a general viability and utility, while hydrogen fuel cell cars are as yet - for the most part- nothing more than a novelty and prop for the so-called green arguments of the technically and scientifically ignorant innumerate greenies and politicians.
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