A Jupiter 8 sales advertisement
A Jupiter 8 on television
The Jupiter 8 was a two-seat sports car designed by the inhabitants of the planet 892-IV. It was first viewed by the crew of the USS Enterprise in the television news footage upon entering orbit of the planet.
Described as "Royal Comfort" and "unexcelled in its field," it had a conventional internal combustion engine with 456 horsepower, a super-flow automatic transmission, a super-glide suspension system, and super-grip white sidewall tires. Upon reading an advertisement in The Gallian, which described the Jupiter 8's features, the Enterprise landing party determined that its power source was, in part, the cause for the planet's smog. (TOS: "Bread and Circuses")
Background
The Jupiter 8 was "played" by the Reactor, a custom aluminum show car designed by Gene Winfield and completed in 1965. The Reactor was based on a 1956 Citroën DS chassis and powered by a Chevrolet Corvair engine. The hand-built car featured electronically-operated doors, hood and roof. It was painted metallic green. The car also made an appearance in the 1968 Mission: Impossible episode, "The Freeze" (which also referenced the drug cordrazine). The Reactor still exists and was featured in the 2005 Bilsport Performance and Custom Motor Show in Jönköping, Sweden.
Not long after building the Reactor and getting into the Hollywood scene, Gene Whitfield went to work for AMT, which constructed the shuttlecraft Galileo and the Klingon battlecruiser models.