VW Diesel-Electric Concept Car Gets 261 MPG

[muriel_volestrangler]

The coolest thing about this car is the drivetrain. The diesel-electric combo features a 2-cylinder TDI engine with a displacement of just 0.8 liters. It’s essentially the company’s ubiquitous 1.6-liter engine cut in half, and it’s bolted to a seven-speed DSG gearbox. The engine is good for 48 horsepower and 88 pound-feet of torque.

The electric drivetrain sports a 20-kilowatt (27-horsepower) electric motor that draws power from a lithium-ion battery of undisclosed size. It’s a plug-in hybrid, and VW says the XL1 can go 35 kilometers (21 miles) in electricity alone.

This combination provides remarkable efficiency. Fuel economy is pegged at 0.9 liters per 100 kilometers, which comes to 261 mpg by our math. Emissions are just 24 grams of CO2 per kilometer. More remarkably, VW says the 1,700-pound XL1 can cruise at 62 mph on just 8.4 horsepower. That’s about half what the Golf TDI requires. Under electric power, the car needs less than 0.1 kilowatt-hour to go one kilometer.

Stomp on it and the electric motor assists the diesel engine in accelerating, and VW says the XL1 will do zero to 60 in 11.9 seconds. Top speed is limited to 100 mph.

http://www.wired.com/autopia/2011/01/vw-xl1-concept-car/

It has 2 seats, but side by side, where earlier models had tandem seats - and a production model would be far more likely to sell with side-by-side seats.

[OnlinePoker]

1. Even better if you use an imperial gallon...315 mpg. n/t

[Old and In the Way]

2. Sounds like a winner.

I hope VW gets this into production ASAP. They could expect to sell them at a premium with that kind of mileage performance. The CO2 specs sound weird, though. 24 grams of CO2 per kilometer? Sounds high.

[mike_c]

4. most of the carbon in the fuel is emitted as CO2...

...if combustion is complete, so that would only be high if the vehicle burns less than 24 g fuel in a km. Lets see, roughly 6.2 lb/gal for gasoline, or 2.8 kg. At 250 miles/gallon (rounded to make the calcs simpler) that's about 2.8 kg fuel to travel about 250 miles, or 11.6 grams fuel each mile or about 18.5 g fuel/km. If every single carbon atom ends up as CO₂, that's only about 18 g or so of CO₂, so you're right, 24 g does sound high. But these were pretty much "back of the envelope" estimates, so it's at least close to the right ballpark. Does that sound about right to you?

This does give a good idea of how energy dense fossil hydrocarbons are, though. Imagine carrying roughly a ton of automobile for a kilometer using only 18.5 g of fuel! That's only 1/24 of a lb!

[muriel_volestrangler]

6. I think this works out - remember this is diesel, not gasoline

If you burn a litre of diesel this will produce 2.6391 kgs of carbon dioxide. Petrol has a lower carbon content and so produces 2.3035 kgs of CO2.

http://www.comcar.co.uk/newcar/companycar/poolresults/co2litre.cfm?clk=1&fueltype=diesel

The fuel economy is 0.9 l/100km; so that's 0.9 * 2639.1 / 100 = 23.8 g/km.

Or using your method:

Diesel weighs about 7 lb/gallon

Typical formula for diesel: C16H34, so 1g of diesel produces (44/12) * (12*16)/(12*16+34) = 3.12g CO2

7/2.2 kg to travel 261 miles = 12.2 g fuel/mile = 7.62g fuel/km = 23.8 CO2/km

[mike_c]

9. yup, more carbon in diesel than in gasoline....

I didn't know that! As you say, that would explain most of the difference between my crude estimate and your calculations! :toast:

[HysteryDiagnosis]

7. If they really wanted to they could....

http://www.hy-drive.com/

[Old and In the Way]

8. Thanks for the explanation Mike!

I guess I never realized how much CO2 output each car contributes on a per km basis. Thank Gawd it's colorless or we'd be in a dense, complete fog while driving.

[hlthe2b]

3. Gotta have side-by-side seats---so my doggy girl....

can ride shot-gun! ;)

[DCKit]

5. I see the oil lobby is busy unreccing. nt

[Lorien]

10. It's sitting in front of a building that appears to be wearing a condom

[ProgressiveProfessor]

11. Physics say the number is a lie

But overall it should be quite efficient

[muriel_volestrangler]

12. Why should it be a lie?

It has a drag coefficient of 0.186, so it's very efficient at a steady speed. Its 20kW electric motor can do a lot of the work in acceleration (and I guess it uses regenerative braking), so you don't need a lot of power out of the diesel engine for acceleration, and it can recharge efficiently.

It is possible that the figure is misleading because the test allows partial discharge of a fully-charged battery; I'm trying to understand the implications of this: http://www.interregs.com/spotlight.php?id=90 .

[ProgressiveProfessor]

13. Look at the energy content of the fuel vice the work done

Also there friction from real world tires, less than perfect roads etc.

This looks to be an interesting evolutionary development and I think it is a good thing. However the marketing bubbas (as always) are using things out of context. This in turn creates false hopes and excessive expectations, which is a bad thing.

This also happens a lot in the alternative energy world. New and exciting press releases about lab results and potential products that never make to the market or when they do can not match the original hype. There is often nothing wrong with the product or the technology, just that it was oversold. I say that as a guy with a large solar field. Its a solid technology, produces as expected etc, but one could drown in the snake oil.

[kristopher]

14. Physics tells us nothing without all the variables in place.

The article tells us nothing of how they arrive at the numbers and what assumptions underpin their method of mileage calculation and CO2 emissions.

The vehicle is a plug-in hybrid and therefore is presumably using grid electricity as an input. Without knowing the parameters being used we can't judge the numbers presented at all. It is a futile effort.

[happyslug]

15. VW had been an advocate of smaller engines for years

The Lupo was their car in the 1990s that did 100 km per 3 liters of gas, roughly 78mpg. One of its quirks was when the engine was NOT in use, it turned off thus saving fuel, for example waiting for a red light to change the engine would shut off, then when you touched the gas pedal the engine would be re-started. Another quirk was its automated standard transmission tied to a diesel engine. When I said Automated Standard Transmission I do NOT mean an automatic, but a computer driven manual transmission, where the switch of gears is controlled by a computer. The SMART car has a similar transmission.

More on the Lupo: VW stop making it for, once the fanatics of fuel economy had theirs (And then only in Europe it was never imported into the US), the car was expensive to produce compared to other cars of its general size (Those features that made it most efficient was expensive to produce and did not have the glamor or the hybrids).
http://en.wikipedia.org/wiki/Volkswagen_Lupo

The Lupo was a "City Car" like the SMART and the Ford KA (Another car NOT sold in the US, but Ford had plans during the 2008 gas price run up, but has since canceled those plans).

The Lupo, the SMART, and the Ford KA, are all based on the concept that the best way to improve fuel economy is to make a smaller car, with smaller engines and smaller transmissions. Between those tree "Smaller" you get a car with much more fuel economy, but a car that has a hard time reaching 50 mph (Thus called "City Cars" in Europe). One of the problems with the SMART Car is that it is really NOT design to operate at 50, but the EPA test is set for 50 mph. The only way these cars can get to 50 mph is to over rev the engine (all these cars can hit 50 mph, just like most cars on the streets of the US today can hit 100 mph). Over revving the engine hurts the fuel economy (especially for a car designed for 30 mph traffic) and thus these cars do NOT do good on the EPA fuel economy tests. Hybrids suffer a similar problem, but in reverse, hybrids do better on the EPA tests then they do in real life, much more then other cars.

Just a comment on why this car does as good as it does in Europe, but will have a much lower EPA fuel mileage if and when it is sold in the US.

[Nihil]

16. Thank you - some very good points there. (n/t)

:toast: