VentureBeat

American automakers have finally learned that fuel efficiency and environmental friendliness count, turning the yearly Detroit Auto Show, which started Sunday, into a lineup of cleantech exhibitions.

Among big-company prototypes like the Chevy Volt and Cadillac Provoq are a handful of smaller firms making significant headway. Following is a brief lineup of the ones we thought were most interesting:

Coskata
A mere two years old, ethanol producer Coskata has managed to attract an investment from General Motors, which it announced at the event.

This isn’t your run-of-the-mill ethanol company. Like cellulosic ethanol companies, Coskata can convert wood and random organic debris into fuel. However, it uses its own proprietary gasification technology to turn this raw material into a synthesis gas, which is then cooled for “fermentation,” during which microorganisms convert the gas to ethanol.

The company says it can run this process very cheaply — for less than a dollar per gallon. The materials it can use include both regular biomass (such as wood chips) and municipal waste streams. To prove the concept, Coskata will initially build a 40,000 gallon per year pilot plant.

The specific amount of GM’s investment was not disclosed. Coskata’s previous investors include Khosla Ventures, GreatPoint Ventures, and Advanced Technology Ventures, who put $17 million into the company. It’s based in Warrenville, Illinois.

EcoMotors
A team with engineering experience at European automakers Volkswagen and Audi is working on a diesel engine that could be efficient enough to be competitive, on a miles-per-gallon basis, with plug-in hybrid technologies.

EcoMotors says its engines, due on the market in 2011, will get about 100 miles per gallon on fuel alone. It’s also planning its own hybrid adaptations that will be even more fuel-efficient.

Diesel engines are often overlooked in the clean-fuel furor. However, they deserve more attention: Not only are they used in virtually all trucks, they’ve also been growing in popularity in consumer vehicles over the last few years.

As with Coskata, Khosla Ventures is an investor in this company, which is based in Menlo Park, Calif. As it happens, Khosla is also an investor in another diesel-cleantech company we recently reported on, called Nanostellar.

Fisker Automotive
When we recently mentioned Fisker Automotive, we had no idea that star VC firm Kleiner Perkins Caufield & Byers had plowed more than $10 million into the company, an investment just disclosed at the auto show. The exact amount wasn’t revealed. Palo Alto Ventures has also invested in the company.

Fisker plans to significantly undercut potential rival Tesla Motors’ $98,000 all-electric Roadster by charging only $80,000 for its luxury plug-in hybrid. (For the overly rich: That’s sarcasm. $80,000 is a lot of money.)

The remaining details: A 0-60 mph acceleration time of 5.8 seconds (slow for an electric vehicle, but comparable to most combustion-engine sports cars), a sustainable speed of 125 miles per hour, and a 50-mile range if using only battery power. Perhaps most importantly, the car is gorgeous, as seen below.

Unfortunately, the car won’t be available until late in 2009. Fisker, which is based in Irvine, Calif., plans on manufacturing about 15,000 a year.