Detroit—Left with vacant space to fill at this month’s annual auto show, desperate organizers chose to fill it with an unusual commodity in this horsepower-hungry town: green cars.

The entire 70,000-square-foot basement of Detroit’s battered Cobo Hall convention center will be filled with a test track that winds through waterfalls and trees. Visitors can drive various hybrid, electric, and green cars, slowly, while carmaker reps or professional drivers sit next to them and pitch the product. It’s the first time Detroit has offered a section for green cars—unlike some other shows, including last summer’s London Motor Show—but the withdrawal of several carmakers, including Nissan, allowed every carmaker who wanted space to exhibit on the main floor.

Media days for the internationally watched show kick off on Sunday, Jan 11. Here’s a preview of the hybrids and electric vehicles that will appear. Check back for breaking news and updates as they come.

Mercedes-Benz

The MercedesS400 BlueHybrid, the first hybrid from the German luxury-car maker, uses a lithium ion battery pack for idle-stop and takeoff assist. The lithium cells are a first, but it’s hardly a full hybrid like the Toyota Prius. Mercedes will also show the BlueZero E-Cell concept car, a small, full electric hatchback.

Incidentally, the Germans chose not to hold a large press event for the media. Instead, they planned a more select, invitation-only soiree the night before, to be held at the recently restored historic Book-Cadillac Hotel, now a Westin. But guests were hardly thrilled on Friday when scores of them got calls from Benz’s PR agency to DIS-invite them from the event. Seems that someone got confused over the legal capacity of the space, and they were way over fire code. Oops…

Lexus

The first images of the Lexus HS250h, an upcoming hybrid-only model from the luxury carmaker, were recently revealed in a Japanese magazine.

The luxury division of Toyota will show a new hybrid sedan with unique styling called the Lexus HS250h, reportedly the marquee’s first dedicated hybrid. Rumor says this will be effectively a luxury sedan version of the 2010 Prius being unveiled a day later.

Chrysler

The Dodge EV, one vehicle in a wave of electric cars announced by Chrysler.

Pinning down the plans of the beleaguered automaker, whose sales last month fell 53% compared to the previous December’s, has been hard. The latest rumor says they’ll show an all-electric version of the Jeep Patriot crossover, which would be a fourth electric vehicle to add to the three electric concepts the company unveiled in September.

General Motors

Two years ago, GM unveiled the concept version of the Chevrolet Volt. This year, the company will show the production version—still two years away from hitting dealerships.

Monday is the big day for hybrid news, kicked off by a GM press conference listed only as a “technical announcement”. But BusinessWeek magazine appears to have broken the embargo: It reports that GM will unveil a small Cadillac coupe on the platform of the Chevrolet Volt plug-in hybrid. GM is also expected to announce that Compact Power Inc. will be the battery supplier for the Volt, with cells supplied by LG Chem. Cell maker A123, working with Continental Inc., had been the other contender for that crucial contract. And GM may have further surprises up its sleeve as well.

BYD

BYD’s showing of the F3DM will give Detroit attendees a chance to peruse a Chinese-made plug-in hybrid.

Following GM will be BYD Auto, the Chinese company that last fall launched the very first mass-production plug-in hybrid in the world. It will display both its F3DM plug-in hybrid sedan, and a new E6 electric crossover vehicle. Executives will describe its lithium iron phosphate cells, and the Dual Mode plug-in hybrid system. BYD might be dismissed as just another Chinese car company (there are several dozen), except that famed investor Warren Buffet acquired a 10-percent stake in its parent company last September. The car company is a subsidiary of BYD Company Ltd., the world’s second largest producer of rechargeable batteries—unlike GM, which has to buy its cells from other companies.

Toyota

The 2010 Prius may be the single most important vehicle at the show for hybrid fans.

One of the most eagerly awaited cars at Detroit is the third-generation Prius. While a photo or two has slipped out, little is otherwise known about the car’s size, powertrain, or features. The car is slightly larger than the current model, but as yet, rumors of a larger engine, more powerful electric motors, and even a lithium ion battery pack are no more than speculation. Toyota is holding its own parallel events during the previews, called Prius Connection, for owners, fans, and influential media. As the definitive, even stereotypical, image of a hybrid, the 2010 Prius may be the single most important vehicle at the show for hybrid fans.

As announced yesterday, Toyota will also reveal the all-electric version of its well-received iQ mini-car.

Fisker

The Fisker Karma plug-in hybrid may be mere months away from production.

Less important to the global industry, but undeniably sexier than the Prius, Fisker’s sleek Karma four-door luxury performance sedan was unveiled here a year ago—with absolutely no technical details. Industry insiders snickered as former BMW designer Henrik Fisker said his plug-in hybrid would go into production at the end of 2009, an astoundingly short schedule. But a year later, the company is sticking to that schedule, promising to deliver the first production cars to paying customers this December. A few more technical details are known—it will have a turbocharged, direct-injection 2.0-liter GM EcoTec four-cylinder engine to run its generator, for example—but the company has yet to reveal any details of the 22.6-kilowatt-hour battery pack. Fisker plans to reveal a plug-in hybrid convertible concept as well.

Honda

Honda’s “Prius-Killer,” the 2009 Honda Insight.

The other important hybrid to appear on the floor will be the production version of the 2009 Honda Insight, which the company says will be the lowest-cost hybrid on sale in the US. A five-door subcompact with unique style, the Insight is the first of several vehicles that Honda will build on a dedicated hybrid platform—the next will be the sporty two-seater CR-Z. Few technical details have been released as yet, and Honda isn’t planning to hold any kind of event. The car will be there, it will hand out a press release to journalists, and that will be that. Honda has always had straightforward, factual press events, and this new approach—utter minimalism during a show pared of its flash, its sizzle, and its showmanship—may reflect the new reality of the industry as well as anything.