13. Toyota AXV-IV
Unveiled at the 1991 Tokyo Motor Show, the Toyota AXV-IV concept showcased a featherweight design aimed at hyper-efficient city driving. (global.toyota) Powered by an 804cc two-stroke engine producing 64 horsepower, it utilized lightweight materials like aluminum and magnesium to achieve a curb weight of just 450 kilograms. Despite its innovative approach, the world wasn’t ready for such extreme minimalism, and the AXV-IV’s vision eventually faded into history. (autos.yahoo.com)