newly updated Super Efficient Vehicle concept, now dubbed the XL1, which -- after a great deal of fuzzy math, we're sure -- is rated at a 313MPG fuel efficiency and produces only 24g of CO2 per kilometer traveled. There's an electric motor and a TDI diesel engine making all the buzzing and roaring noises inside, while the overall body design is focused on making the car as light and as aerodynamic as possible. Volkswagen has achieved a 795kg curb weight by using carbon fiber, magnesium, ceramics, and aluminum to shave down any excess portliness from the XL1, while wind-tunnel testing and optimizations have resulted in a rather exemplary 0.186 drag coefficient. It's rare to see such attributes on anything outside the supercar realm, but then there's a reason why this PHEV is still only a concept. FOF.
Update: Oh bother. Turns out Volkswagen's mileage claim is based on Imperial gallons, which are 1.2 times the size of the American stuff, meaning that the XL1 actually measures in at 260MPG when viewed through US glasses. Now do you see why the rest of the world has gone metric?