Take one gallon of diesel fuel and drive 313 miles - that is the claim of Volkswagen's XL1 concept car:
The XL1, which seats two adults, combines a 0.8 litre two cylinder diesel engine with an electric motor.
The car is constructed around a carbon fibre reinforced polymer monocoque to reduce the weight to just 795 kilos.
These two videos show what the car looks like:
However, there is something about this announcement that feels not-quite-right. If they are capable of 300 MPG, wouldn't it seem reasonable that there would already be a predecessor, like a 100 MPG car, on the road? It seems like 100 MPG would be easy if you can do 300 MPG in a concept car.
And in Volkwagen's case, the 100 MPG car does exist. It is the L1. It has been rumored and teased for a decade as a production car - the latest production date is 2013:
But the L1 is tiny, low and narrow. It has tandem seating, and it weighs only 380 kg - half that of the XL1.
So if the tiny, low, narrow, tandem, featherweight L1 gets only 170 MPG, how can the much bigger, twice as heavy XL1 get 313 MPG?
If you would like to follow Brainstuff on Twitter or Facebook, here are the links: