According to Car Central [1] in Australia, Volkswagen is bringing a concept car to market that travels 100KM (62 miles) on 1L (.26 gallons) of fuel. That works out to about 234MPG.

The 300CC one cylinder diesel engine car is built using lightweight materials (carbon or possibly magnesium according to some reports) and weighs only 300KG (660LBS). According to the report, Volkswagen only plans to make about 1000 per year, and the cost will be $20K-$30K EUR (approx. $31K-$47K USD).