2002 Cadillac Cien
In 2002, Cadillac introduced its mid-engine supercar with a V12 engine inspired by an F-22 fighter jet. It was a great concept car to commemorate the 100th anniversary of the brand. Customers were sad to hear that they could not purchase anything exciting. The Ciel appeared in a number of video games, but its engine, chassis, fun, or tech did not show up again in any actual car.
1997 Dodge Copperhead
Dodge followed the success of the Viper with the Copperhead concept car, which was introduced at the 1997 North American International Auto Show. It was supposed to be a slimmer Viper with a 220 hp V6 engine under the hood. It was focused on driving and handling pleasure, although the project got canceled in 2000. Dodge did not give us a fun-to-drive roadster but the boring Avenger and Stratus. Its engine and mechanicals appeared in other Dodge models but without the same verve or zest.