Automakers watch visitor reactions at those shows to help determine which cars will be popular in production form. The million-plus showgoers here come from all walks of life and various ages groups and constitute a wonderful built-in audience for vehicle producers.
For instance, reaction at last year's Chicago Auto Show to a concept Chevrolet Camaro and Plymouth Barracuda helped convince Chevy to bring back its discontinued Camaro and DaimlerChrysler's Chrysler unit to build a modern version of its 1970s Dodge Challenger.
Moreover, concept vehicles help draw visitors to exhibit areas, where regular production models are displayed.
The most radical concept vehicles were at the 1950s show here. Some were only futuristic styling exercises, without even an engine. No wonder they were called "dream cars" -- not "concepts."
However, automakers decided in the 1960s that it would be more practical and far less costly to display concept cars that were close to being production models.
These are among key concept cars scheduled to be at the show:
Acura Advanced Sports Car: It's a glimpse at Acura's next advanced sports car. A sexy two-seater spices up any automaker's vehicle line, even though relatively few are sold. Acura has not offered a sports car since it dropped its NSX mid-engine V-6 two-seater last year. This concept is significantly different than the NSX. Its front-mounted V-10 is the most powerful engine in Acura history.
Chevrolet Camaro Convertible: The retro-style Camaro hardtop was a major hit at last year's show, so Chevy has decided to display a convertible concept version of that car to help maintain strong interest in it until it's produced in 2009.
Chevrolet Volt: Chevy (really General Motors) tries to outdo Japanese hybrid gasoline/electric production vehicles with this rakish-looking concept. It has a pure electric powertrain that gets energy from plugging it in at home or work -- or from an onboard generator powered by a small gasoline engine. Viable batteries aren't ready yet for the Volt, but Chevy says it expects they will be by 2010 or 2012.
Chrysler Nassau: It's a four-door blend of the racy Chrysler Crossfire two-seat sports car and Chrysler Pacifica four-door SUV and has coupe-like styling. It's based on the Chrysler 300 platform and might be the next generation Chrysler 300. The techno-style interior draws from such devices as MP3 players and advanced cell phones.
Ford Airstream: This is one of the most controversial concepts. It's a superslick hybrid with a plug-in powertrain and hydrogen-powered power cell but looks like a chrome-painted bread box with orange-trimmed windows and a digital lava lamp on the floor.
Ford Interceptor: It's built on a stretched Ford Mustang chassis, but is a four-seat family model. However, the chopped (lowered) roof gives it a sporty look, and a 400-500 horsepower V-8 resides under the massive hood. It's got the elegance of some 1960s Ford sedans.
Honda Accord Concept Coupe: This rakish model is close to the production coupe that goes on sale this fall. A complex front end and projector beam headlights recessed into the fenders are attention-grabbers. A wildly sloping roofline draws eyes to the short, neat rear end. An advanced body structure provides added protection, especially in frontal collisions with vehicles of various sizes.
Honda Remix: This four-cylinder, front-drive concept combines two-seat sports car capabilities with daily functionality. Smooth, soft lines blend with a rear wraparound canopy that allows a decent amount of storage space.
Hyundai HCD10 Helion: This two-door hatchback is modeled after an insect's exoskeleton for an ultra-rugged appearance. A 236-horsepower diesel engine and four-wheel drive make it quick as a water bug.
Jeep Trailhawk: This brawny-but-stylish concept is built on a long Jeep Wrangler Unlimited chassis. It has plenty of ground clearance for rough off-road driving, but also a sporty low-slung roofline. Removable roof panels allow open-air driving. Some concepts never fully die -- the Trailhawk was partly inspired by the sleek 1998 Jeepster concept. Too bad that one wasn't produced.
Kia Kue: The futuristic-looking Kue is described as a "pumped-up crossover vehicle" and probably provides a look into future Kia styling. Not long ago, styling wasn't all that important to South Korean automakers. But the Kue shows that design is becoming an important consideration. Note the huge 22-inch wheels and tires.
Lincoln MKR: This one also is built on a stretched Ford Mustang platform. Its glass roof isn't practical, but its engine, suspension and platform could be used for a production Lincoln. It's grille is reminiscent of classic Lincolns, which never had the MKR's twin-turbocharged 3.5-liter, 415-horsepower V-6.
Mazda Nagare: This funky looking "flow theme" concept looks like it got caught in a 250 mph headwind that swept back its body. It isn't based on any Mazda production model, and the automaker says it suggests where its design will be in 2020. That's an awfully long-shot projection.
Mazda Ryuga: Mazda says this one is a more down-to-earth interpretation of what future Mazdas might look like. The Ryuga has a long flip-up door that opens up both the front- and rear-seat areas -- generally an auto show styling trick to fully reveal a lavish interior.
Toyota FT-HS: If this concept doesn't stop show visitors in their tracks, nothing will. Toyota thinks the FT-HS might be an appealing sports car for our new century, combining ecology and emotion. It's a fast, wild-looking, front-engine, rear-drive aerodynamic hybrid with a 400-horsepower V-6 and next-generation hybrid technology. Some think it hints at a new Toyota Supra sports car. A beam down the middle of the interior separates driver and passenger cockpits, and there's a hubless steering wheel with paddle shifters for a semi-automatic transmission.
