It's called the Volkswagen 1L and it only cost 600$. It will be the most economic car in the world, and is street worthy. The car only seats one, but at this price you can honestly buy a bunch for the family.
Gas tank capacity = 1.7 gallons
Speed = 62 - 74.6 Miles/hour
Fuel efficiency = 258 miles/gallon
Travel distance with a full tank = 404 miles