DETROIT (AP) -- Prototype cars - also called "concepts" - appear at every auto show. They're a way for companies to test ideas, gauge reaction and hint at future designs.
Audi, Nissan, Kia, Volkswagen and others will have concept cars at this year's Detroit auto show, which opens to the public Jan. 18. Some will be nearly identical to the cars that wind up in dealerships; others will be more outlandish.
Here are some past prototypes that debuted in Detroit over the last decade, and what happened afterward:
Five That Made It:
CHEVROLET VOLT (2007) - GM's revolutionary electric car with a backup gas engine debuted as a sexy concept in 2007. So, fans were disappointed with the dull looks of the production version revealed a year later. The car required significant design changes to improve its efficiency. But at least the idea made it to market. The Volt went on sale in 2010.
FISKER KARMA (2008) - The hybrid sports car, with its long hood and flowing lines, wowed crowds as a concept car in 2008. The $95,000 Karma went on sale three years later. But it was plagued with safety recalls, and Fisker eventually halted production and filed for bankruptcy protection. That wasn't the Karma's final chapter, however. At last year's auto show, a company called VL Automotive showed the Destino - a Karma body with a Corvette engine under the hood. This year, VL Automotive is expected to show off a convertible Destino.
CADILLAC CONVERJ (2009) - A rakish Cadillac with the Chevy Volt's plug-in hybrid powertrain wowed crowds in 2009, a recession year when there was little to cheer about in the auto industry. The Converj, renamed the ELR, re-emerged in production form at the 2013 show, and is set to go on sale early this year.