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BMW 7-Series Car Review | BMW 7-Series Hydrogen 7 | December 20, 2006

Driven December 2006

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With everyone chest-beating over climate change and automotive corporations getting various degrees of needle over emissions, it seems that the timing couldn't be better for BMW to pop up with a hydrogen combustion engine - housed here in the new 7-Series.

Of course, we've seen BMW's commitment to future fuelling for over a decade, but now the company has seen fit to produce a hydrogen-capable car that looks and goes like a regular Seven, and even to lease it out to a select few. The point being that this looks and feels like a production car, rather than an experimental platform.

The Hydrogen 7 is basically a V12 760Li adapted to contain the necessary pipework to combust hydrogen in its naturally aspirated engine. Thus, as well as a standard petrol fuel tank, you also get a rather large hydrogen tank finagled into the back, cutting legroom on this long-wheelbase chassis to just an inch over a regular Seven.

Uncovered, the hydrogen tank looks like a small aluminium boiler lying prone just under the C-pillar. Liquid hydrogen needs to be kept cool and under pressure, and the tank has a twin-skin construction that uses space-age tin foil and glass fibre, plus 30mm of vacuum to provide insulation equivalent to 17 metres of polystyrene.

Despite BMW's protestations, this car feels different on the move; the usually brawny-but-silky V12 suddenly seems anaemic with just 260bhp at its disposal (the price of hydrogen combustion is horsepower) and the extra bulk to haul about - the extra tank, etc, adding over 200kg.

BMW's engineers have done a fine job of keeping a creditable 47/53 weight split front to back, but it still feels strange through tight corners, especially as we're used to the normal Seven being sprightly for its size.

You might not notice the engine's differences at town speeds, but accelerate hard and you get both a lack of expected power and a surfeit of diesel-style aural clatter. Running on hydrogen, the Seven hits the benchmark in 9.5 seconds and on to an electronically limited 143mph.

But saying that, the Hydrogen Seven otherwise performs impeccably as a large saloon, with none of the weirdness of other future fuellers.

To be fair, BMW is not saying that this car is the magic bullet. The hydrogen tank only allows for a 125-mile range, hence the other 400-mile tankful of petrol, and of course there's an issue because hydrogen isn't readily available. But it opens up the debate. The Hydrogen 7 might not be the future, but it helps us point the way.

Tom Ford

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