High-tech at the Frankfurt auto show

Last week's Frankfurt auto show was dominated by Mercedes-Benz, with its launch of 19 new cars. BMW and Audi tied for second in what the carmakers had to show off. Filling out the German roster was Volkswagen, which hasn't had anything particularly exciting to show off for the last few shows, and Porsche, which sits in its own rarefied atmosphere.

Other manufacturers were there, but didn't have much to show, possibly holding back the good stuff for other shows. The only really interesting concept among the Asian carmakers was the Nissan Mixim. This small, wild-looking, electric-powered car was everything a concept should be--it explored a unique exterior design, put forth a potentially revolutionary powertrain, and used an instrument panel and controls straight from the future. In contrast, Honda showed off its Accord Tourer concept, the next generation of its European Accord wagon. What a yawn.

The only other concept of note was the Mercedes-Benz F700. Actually, Mercedes-Benz calls it a research vehicle, emphasizing how its past research vehicles have contributed real technologies to production models. The exterior design of the F700 takes cues from an older design study called the Bionic car, which was inspired by the shape of the Boxfish. These cues in the F700 aren't immediately apparent, as it's a big sedan whereas the Bionic car was a compact, but if you look at how the A-pillars of the F700 dip into the body, the similarities stand out.

Cadillac got a scoop on Mercedes-Benz, launching its 2008 CTS with vertical light pipes in the headlights, something the F700 also uses to present a unique look at night. GM may struggle, but Cadillac is the brand to watch as it continues to build good quality and incorporate new technology. But the F700 has a lot more than interesting headlights up its sleeve. It takes the video screen instrument cluster already used in the CL- and S-class, kicking it up to the next level. In our review of the CL550, we noted how the virtual speedometer gauge changes over to a night-vision screen, with speed displayed as a horizontal bar below it. The F700 extends the instrument cluster screen across the panel, doing away with mechanical gauges entirely. This change allows for much more flexibility in what is being displayed. For example, if you want to see your engine speed, you can have a tachometer, but if this information isn't of interest, use the space to display detailed music information.

The F700 also fulfills its research vehicle portfolio with a very interesting engine. The DiesOtto uses technology called "homogenous charge compression ignition," which means that, at normal and high loads, it combusts gasoline in its cylinders through compression, like a diesel. At low loads, it uses a standard spark to ignite the gas, like a standard gasoline engine. Compression combustion gives diesel engines their high efficiency, and promises to do the same with the DiesOtto. The numbers thrown around by Mercedes-Benz are amazing, and this isn't a company known for wild claims. The 1.8-liter, four-cylinder DiesOtto in the F700, aided by twin turbos and a small hybrid system, is supposed to generate 238 horsepower, get better than 40 mpg, and push the car to 60 mph in about 7.5 seconds. The DiesOtto will be a revolutionary engine if we ever see it in production.

Mercedes-Benz also claims the DiesOtto will only put out 127 grams per kilometer of CO2, an excellent number compared to current production cars. Carbon emissions were a big theme of the Frankfurt auto show, as well. A lot of the new models shown off by Mercedes-Benz were just current model types with gas-electric and diesel-electric hybrid engines. The company showed off how its new hybrid technology would decrease carbon emissions. BMW had a similar theme, labeling its own engineering Efficient Dynamics. It showed off its smaller-engine gasoline and diesel cars with its grams per kilometer rating, for example, touting the 123d, a 1-series diesel, with a rating of 138 grams of carbon emissions. Unfortunately, BMW has no current plans to bring the 123d to the U.S.

It is, however, bringing the BMW 135i over. This car's performance should be phenomenal, although the exterior isn't much to look at. BMW took its entry-level car, the 1-series, and crammed its brilliant twin turbo 3-liter six-cylinder engine under the hood. Having used that engine in both the 3- and 5-series, I can attest to its smooth power delivery and responsiveness. In a smaller car like the 1-series, acceleration is going to be quicker than quick. And with the benign look of the car, you will surprise the hell out of Porsche drivers.

Click here to see all of our 2007 Frankfurt auto show coverage.