What's good gas mileage? 30 mpg? 40 mpg? The 50-mpg combined rating of the 2011 Toyota Prius, the most fuel-efficient car sold in the U.S. this year?

Nah. How about 261 miles per gallon? Or, for the Europeans in the house, a mere 24 grams of carbon dioxide per kilometer.

You heard right. The Volkswagen XL1 plug-in hybrid concept shown here, being launched at the Quatar Motor Show this week, achieves a fuel efficiency of 0.9 liters per 100 km, which for North Americans translates to a bit more than 260 mpg.

Volkswagen XL1 Concept

Volkswagen XL1 Concept

Designed to build

It's the third iteration of VW's "1-Litre Car" project, which has now spanned almost a decade.

And this one, says the company, is designed so that it could practically be manufactured if there proves to be a market for such a hyper-economical two-seat car.

UPDATE: Just prior to the media launch in Qatar, VW Chairman Ferdinand Piech told reporters the company would build a small run of XL1s, starting in 2013. Initial models will go to Germany and then other European countries. The U.S. and China will follow. Another VW executive said total production volume could be as low as 100 units, however.

Looking like nothing so much as an updated and crisper version of the legendary GM EV1, the XL1 has a long tapered tail, rear wheel spats, and a steeply raked windscreen. VW's aerodynamicists follow the same laws of physics as GM's did, and they managed to eke out a drag coefficient of 0.186.

Half a diesel

Its powertrain is a tiny 0.8-liter two-cylinder TDI turbodiesel producing 47 horsepower--essentially half of a Volkswagen 1.6-liter diesel four. It is paired to a 20-kilowatt electric motor powered by a lithium-ion battery pack (of unspecified capacity) and a seven-speed direct-shift gearbox (DSG).

Volkswagen XL1 Concept

Volkswagen XL1 Concept

VW quotes an all-electric range of up to 22 miles, and a top speed limited to 100 mph. Acceleration from 0 to 62 mph takes 11.9 seconds, tolerable by European standards. .

The body is made of carbon-fiber reinforced polymer (CFRP), using techniques similar to those for Formula 1 racecar tubs.Total vehicle weight is just 1,750 pounds, and that includes the full gamut of safety structures and protection equipment found in any modern vehicle.

Aluminum, ceramic, magnesium

The XL1 is packed with weight- and energy-saving technology, from the LED lights to the aluminum structural and suspension members, ceramic brake disks, and magnesium wheels.

VW's first project along these lines was the 1-Litre Car concept of 2002. Then, in 2009, it showed the L1, an evolution of that theme. The XL1 is clearly a thinly disguised production prototype, launched to gauge market reaction to a car this green that isn't a battery electric vehicle.

Volkswagen XL1 Concept

Volkswagen XL1 Concept

More for Europeans?

This is likely to be a car more for European buyers than for North Americans, where cars are larger and two-seaters have never been more than a tiny fraction of the market.

It is also likely to be hugely expensive, as BMW's somewhat similar carbon-fiber MegaCity all-electric urban car will be.

What's your reaction to the Volkswagen XL1? Would you buy it over a two-seat electric car, especially if it had a lower overall carbon footprint than the electric?

Leave us your thoughts in the Comments below.


UPDATE: [Automotive News (subscription required)]