In more recent times, they've been so much more than that. They still look extreme and showcase blue-sky technology, but concepts now give us a much clearer indication of tomorrow's actual cars.
Now the 2012 auto show season is over, we've picked our favorite ten concepts from this year. Think we've missed an important one? Tell us using the comment section below!
Want to know what a Lexus IS coupe might look like? The LF-CC should give you a pretty good indication. Strip away some of the more extreme features--the razor-sharp front bumper, the crazy mirrors--and you pretty much have the next IS, in coupe form.
We now know a production version is likely to use a new 2.5-liter hybrid drivetrain, and be called the IS 300h. If you thought hybrids were just a little bit boring, the LF-CC should be enough to convince you otherwise.
Technologically we're fairly familiar with the BMW i3--electric drivetrain, carbon-composite body, optional range-extender--but the i3 Coupe brings the concept even closer to production.
It loses two doors from the regular i3 and isn't really a traditional coupe, but BMW says the styling and interior aren't far off being production ready--and we'll see the finished product towards the end of 2013.
A gasoline-engined crossover isn't too special, but VW has demonstrated excellent execution with the Taigun. It's based on the small, light-weight platform of the Volkswagen Up minicar, and uses a similarly-tiny, turbocharged engine.
There's no trick hybrid system or electric drivetrain here-just all-round improvements on a tried and tested formula. The square-jawed lines look great, too.
Smart's concept cars look increasingly production-ready, hinting at the new model which is expected to debut soon. The Forstars has some unusual touches--a projector on the hood being one--but many of the details could find their way onto the production car.
Like all recent Smart concepts, the Forstars uses an electric drivetrain, taken from the current-generation Fortwo Electric Drive. Production Fortwos will come with regular gasoline engines too, but Smart is clearly investing in its EV tech.
Taking the concept of 1960s and 1970s hot-rodded Bugs into the 21st Century, the E-Bugster concept hinted at the now-unveiled Volkswagen Beetle Cabriolet. It has been shown in both roofed and roofless variants in 2012.
Unlike the Cabrio though, the E-Bugster uses an electric drivetrain, adapted from that in the electric Golfs VW is trialing. That means 113 horsepower, a 110-mile range, and a fast charge capability for 35-minute top-ups. Groovy, dude.