For now, as I hit start, the diesel is idle. The only way to tell the XL1 is ready to roll is by reading the gauge cluster visible between the steering wheel. Putting the dual-clutch manual into gear the little car lurches forward, the only sound gravel crunching beneath its narrow, low-friction tires.
As we weave through traffic in Wolfsburg, VW's German home, the XL1 draws plenty of stares from pedestrians and other drivers. The car is so small it's easy to maneuver city streets and though the XL1 has no power steering—too heavy—it's so light as to be surprisingly nimble.
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On local roads, there's little trouble keeping up with traffic, though the real test comes as we turn onto the A1 Autobahn heading toward Berlin.
The good news is that with the vehicle so light, its compact powertrain delivers quicker acceleration than one might expect. It's no rocket but it's quicker than some classic econoboxes that might otherwise leave you fearing for your life on the unlimited German freeways.
Of course, the diesel has finally fired up and, well, no matter how much VW ultimately charges when the XL1 goes on sale you won't confuse it with a similarly priced luxury car.
To save weight, there is almost no sound insulation so the cockpit echoes with the oil-burner's clacking. Happily, as we exit the Autobahn it quickly shuts down and our ears get a respite as we return to battery power.
We can only hope that VW planners opt to sacrifice a few pounds and a couple mpg when the two-seater goes into production. Even if it "only" delivered 255 mpg in final trim would potential buyers be disappointed? Unlikely.
In fact, a final check of the gauges as we pull back into VW headquarters shows that we've been averaging a more thirsty 1.8 liters per 100 km, a mere 138 mpg, due to spending so much of our time racing along the Autobahn under diesel power near to the XL1's top speed of 99 mph.
That said, we'd still be able to make the run from Berlin to Frankfurt—or Los Angeles to San Francisco, for that matter—on well less than three gallons of fuel.
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VW expects to produce just a couple hundred copies of the XL1, enough to log some real-world data about the various technologies the little car uses.
In the years ahead, however, we can expect to see the design influence more mainstream products as the industry struggles to meet increasing mileage and emissions standards around the world.
While 261 mpg requires some real sacrifice from driver and manufacturer alike, the Volkswagen XL1 should help engineers and designers figure out ways to deliver significantly better numbers than the typical automobile delivers today.
—By CNBC Contributor Paul A. Eisenstein. Follow him on Twitter
@DetroitBureau or at thedetroitbureau.com.