How Diesel-Electric Hybrids Work and Why They Aren t on Sale Yet

Diesel Electric Vehicle

Vehicles / December 24, 2016

WOLFSBURG, Germany – At first glance, the Volkswagen XL1 is like any other supercar. It’s long and low — lower, even, than a Lamborghini Aventador — with the same alluring blend of science and art and physics. Getting in requires opening gullwing doors and oh-so-carefully climbing over a wide carbon fiber sill before sliding into a carbon fiber seat with just enough upholstery to approximate comfort.

The interior is more of the same supercar aesthetic. There’s a small, race car-inspired steering wheel (yes, also carbon fiber) framing the usual gauges. The cabin is minimalist and confined, but strangely comforting. It isn’t until you start the car that you sense it’s not what you think. Press the “Engine Start” button and… nothing. There is no engine noise. No chimes or beeps or bongs. The only indication that it’s running is a brief flash of lights on the gauges, the sat-nav blinking on, and the climate fans starting to whir. That’s it.

It’s time to redefine “supercar.”

I shift into drive, hang a right out of the parking lot and get on the gas. The speedometer needle crawls past 20, then 30, then 40 mph. It takes an almost agonizing amount of time to reach these speeds. In less than a minute, as I tool along at a leisurely 60 mph, it becomes obvious that the XL1, despite its sleek, futuristic appearance, has all the sporting pretenses of an asthmatic race horse sucking air through a coffee stirrer.

How could such a vehicle possibly be considered a supercar when it takes more than 12 seconds to reach 60 mph? Because once you’re there, it takes a scant 8.3 horsepower to maintain that speed — one-third that of a Jetta — and you can cruise along there all day while getting the equivalent of 261 mpg. That’s enough to go from San Francisco to Los Angeles and back on less than three gallons of fuel.

It’s time to redefine “supercar, ” a term that now includes VW’s super-efficient diesel-electric hybrid, which goes on sale in Germany and Austria later this year.

VW’s “one liter” car — a vehicle capable of traveling 100 km on one liter of fuel — has been around since 2002. It started as an engineering exercise, a way for the wonks at VW to show off their hyper-efficiency chops. A draft concept debuted, with in-line seating for two — fighter jet-style — and a body that looked like metallic cigar sleeve with windows and wheels. VW followed up a few years later with another concept that was slightly more refined but still completely unfeasible.