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.
Tesla may be first on the market with an all-electric luxury sedan, but Infiniti wants a piece of the pie too. The swoopy styling takes inspiration from Infiniti's other recent concept, the Emerg-E plug-in sports car.
With a 100 kW electric motor (134 horsepower) and a Nissan Leaf-derived platform it isn't the bespoke sedan a Tesla Model S is, but the LE Concept does offer wireless inductive charging as a standard feature--we wonder if the LE will make production?
If you're looking for hints as to what the next-generation Toyota Prius might look like, you could start with the NS4 Concept unveiled early in the year.
First shown at the Detroit Auto Show, the NS4 is a Camry-sized plug-in hybrid sedan, with a lightweight powertrain and technology by the boat-load. If this is what the next Camry or Prius will be like, we're rather looking forward to it...
Morgan is the odd one out on this list. Not only is the quaint English company tiny compared to giants like Toyota and Volkswagen, but its electric concept is distinctly retro in appearance.
The Worcestershire firm has even given the Plus E a manual transmission, which it says offers a more connected driving experience than a single-gear system. We think typical Morgan owners will probably approve. Range is 100 miles, and it'll top 120 mph.
Another unique Toyota concept, and another which may offer details for the next Prius. The FT-Bh is much smaller than the NS4, at roughly the size of a Yaris, but it's significantly more aerodynamic than today's hybrids.
That bodywork may look like something you'd find crawling around on the ocean floor, but it results in a low 0.235 drag coefficient. The engine is a tiny 1.0 liter, 2-cylinder unit with hybrid and plug-in hybrid options, and predicted fuel economy is 112 mpg even on the hybrid...
It's hard to believe that the Acura NSX was now launched almost a year ago. Appealing to green fans and gearheads alike, it resurrects one of Honda's most sought-after models, the original NSX supercar.
The statistics out-punch the original's 276-hp 3.0 V-6, though--a V-6 returns, but this time it's hybrid-assisted and sends power through Honda's Super Hybrid All-Wheel Drive system. The greenest supercar yet? Could be...