Gizmag reports on a modified Caterham Seven Roadsport, recently entered into Shell's Eco-Marathon.  Rather than going for a nippy 0-60 time, fuel economy was the name of the game and the Seven returned over 130 mpg.  The way petrol prices are going round here, perhaps they'll share some of their expertise.
Also reported at Channel 4, Tech E Blog, Reuters, CarKeys, Motortorque, Jalopnik, New Zealand Herald.