Photos: Concepts at the 2008 Detroit auto show

Audi didn't have to stretch to create this concept. It took its existing R8 car and replaced the gasoline engine with the V12 TDI engine used in its Le Mans winning race car. Audi seems to be testing the waters by showing this car off as a concept, but judging from the reception, it will go into production.

The Furai continues Mazda's line of Nagare-themed concept cars. The Furai is specced out as a flex-fuel car with a 450 horsepower triple rotary engine. Mazda has no plans to produce the Furai as a race or street car.

The Zeo is one of three concepts shown off by Chrysler, demonstrating the new direction of the company after the recent takeover by Cerberus Holdings. The ZEO is specified as an electric vehicle. Chrysler says it would have a range greater than 250 miles with its lithium-ion batteries.

We don't need much convincing of Mitsubishi's sports car prowess, but the company showed off the sleek-looking Concept-RA. The Concept-RA explores the idea of using a diesel engine, in this case a 2.2-liter clean-burning four cylinder, in a sports car.

As the Concept-RA uses Mitsubishi's new twin clutch transmission, the car has paddle shifters, doing away with a center-mounted stick. The instrument cluster is kept tightly focused on the driver, with no real center stack.

Cadillac's new CTS is an exceptional sedan, even winning our Tech Car of the Year award. The company capitalizes on its success by trying out a coupe version of the car, emphasizing its performance characteristics.

Ford is looking to the future, developing the Verve as its next-generation small car. We've seen earlier iterations at other car shows. The Verve indicates a new European design language being adopted by the company. A car based on the Verve concept will come to the U.S. in 2010.

The EcoVoyager looks like a convergence between the minivan and sedan. Chrysler specifies an electric powertrain, using lithium-ion batteries and a hydrogen fuel cell to give the concept over 300 emission-free miles.

Probably the worst-kept secret in the automotive industry, Nissan was giving sneak peeks of the Forum for the last three months. The car explores a design for a next-generation minivan.

We're not crazy about the Forum's exterior, but the cabin looks like a comfortable place to sit. The middle-row seats can swivel around, making a rear conversation area.

The LRX shows Land Rover's desire to extend its range of vehicles into a more conventional road model. It is also a recognition of the need for more environmentally sound cars. Land Rover specifies a 2-liter turbo diesel powertrain complemented by a hybrid system.

Mercedes-Benz showed off two versions of the Vision GLK, the Freeside and the Townside. Both cars explore the idea of a compact diesel-powered SUV as a smaller alternative to the company's ML-class. The GLK will probably be produced little changed from its concept form.

Although the Provoq demonstrates a solid crossover design, the fact that it uses GM's E-Flex powertrain with a fuel-cell range extender shows that it won't be hitting the road any time soon. E-Flex still needs serious development to be practical.

Lincoln showed off new creative energy with its range of MK-designated cars, with the MKT the latest effort. The vehicle is a crossover and the "T" stands for touring. The MKT is powered by a 3.5-liter turbo-charged V-6.

The MKT's designers drew influence from the iPhone for the center stack and used LEDs around the instrument cluster to give it a look like jewelry. The center stack actually uses rear projection onto a curved, touch-control surface.

Honda calls this next version of its Pilot SUV a prototype, putting it in the concept category, but it will be released in much this same form as a 2009 model update later this year. The Pilot's six-cylinder engine improves economy by operating in four- and three-cylinder modes when appropriate.

Ford rolled out this concept to demonstrate its new fuel-saving technologies, such as direct injection and a six-speed automatic transmission. We were mostly impressed by little benches that pull out of the bumper, making an impromptu picnic table.

We also liked the instrumentation in the cabin of the Explorer America, complete with big, domed compass that looks suitable for a spaceship.

With the A-Bat, Toyota returns to the mini-truck style it made popular in the 1970s. Environmental concerns inspired Toyota to make this small truck and fit it with a four-cylinder hybrid powertrain, similar to that used in the Camry Hybrid.

Toyota envisions the A-Bat as a multipurpose car for the city and off-road. The cabin is designed to be comfortable for long trips. A portable navigation device is fitted to the dashboard, with built-in Wi-Fi. Dashboard-mounted solar panels help recharge the navigation unit.

The two-seater Renegade uses a lightweight body and is powered by an electric motor. It can go 40 miles on its lithium-ion battery pack, while a Bluetec diesel engine generator works as a range extender. Chrysler says it can get 110 mpg.

With the HX, even Hummer is touting environmental responsibility. The HX is the smallest Hummer yet, but maintains the brand's off-road credentials. It is powered by a new V-6 designed to run off of ethanol and various ethanol-gasoline blends.

The HX designers were inspired by aircraft construction for the interior, using lightweight materials, such as drilled aluminum frames to support the seats. As a look toward the future, there is no conventional stereo head unit in the HX--it merely has a port for an iPod or other MP3 player.