Test Drive: BMW's Hydrogen 7 sedan

Nearly a hundred Hydrogen 7 sedans are on the road for testing, with hydrogen fueling their internal-combustion engines

by James M. Flammang

BMW Hydrogen 7 sedan (note storage tank)

DETROIT - During the 2008 SAE World Congress, which draws engineers and other technical experts from around the world, BMW held a news conference to promote its alternative-fuel programs. In addition to discussing BMW's BluePerformance diesel-engine plans, the company used this occasion to promote its Hydrogen 7 sedan.

Ever since 2002, BMW has been developing a modest fleet of hydrogen-powered 7-Series sedans (the German automaker's most luxurious model). None of them are for sale. They're used solely for test-drives and demonstrations. A number of high-profile people in business, politics, and entertainment have been given the keys to a Hydrogen 7 sedan for a three-week trial.

Unlike most experimental cars that run on hydrogen, which are set up for fuel-cell operation, BMW's Hydrogen 7 contains a conventional internal-combustion engine. Two versions have been released: a bi-fuel (dual-mode) sedan that can run on either hydrogen or gasoline, or a new mono-fuel model that operates only with hydrogen.

Under the hood sits a 6.0-liter V-12 engine, re-engineered to run on hydrogen. BMW claims near-zero emissions for the mono-fuel version.

As a rule, hydrogen-powered automobiles feel little different from those that run on gasoline. At least, that's been true of experimental fuel-cell models.

BMW's Hydrogen 7 can't quite make that claim. As the company representative pointed out without hesitation, this sedan's V-12? engine doesn't feel quite like its gasoline-fueled counterpart. Combustion with hydrogen is "harder," he explained. Therefore, a slightly harsh sensation occurs when stepping on the gas: not particularly troubling, but not quite BMW-like, either.

There's also a bit more engine sound; though again, it's not noisy enough to create any sort of consternation. Overall, the Hydrogen 7 delivers the same brand of elegant motoring that a "normal" 7-Series sedan provides - coupled with the knowledge that you're driving something unique. Flick the switch between hydrogen and gasoline, however, and some distinct differences are immediately noticeable.

Cargo space is a detriment. The hydrogen supply tank takes up most of the car's trunk space, and even encroaches a bit upon back-seat room. Actually a tank within a tank, the container must hold hydrogen stored as a liquid, at more than 400 degrees below zero.

Whether hydrogen-powered BMWs with internal-combustion engines - or any hydrogen vehicles - ever get to dealerships is impossible to say at this point. Shortage of hydrogen is one big drawback. In order to make its experimental Hydrogen 7 fleet available to journalists and others around the country - and the world - BMW must send a special fuel truck along to handle the refilling. Or, as an alternative, check that the Hydrogen 7's tanks are full to the brim with hydrogen before starting off, and make sure not to run out during a test-drive.

Later in 2008, BMW will introduce two Advanced Diesel models for sale in all 50 states: the X5 xDrive35d and the 335d sedan.

Attention Editors: This complete BMW Hydrogen 7 review is available now for your publication. Please contact us at JF@tirekick.com for details.

© All contents copyright 2008 by Tirekicking Today
Text and photos by James M. Flammang
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