A sporty 4-passenger convertible (originally billed as an Oldsmobile) shows that GM can make a fun small sporty car. The O4 is based on the current Opel Astra platform. More than 2 ft. shorter than the Alero coupe, the O4 maximizes space for its occupants. Twin removable targa tops provide the open-air experience. The rear-hinged doors ease access for back-seat passengers. All gauges are computer generated on an electronic display, and can be changed into different formats. Italian design firm Bertone constructed the O4 for GM.