15 Nov 06
Then there's the fact that you can't park it in a garage for fear of escaping hydrogen building up and exploding. And that hydrogen kept at -253deg C will slowly boil away. BMW says it'll lose half its tank in nine days.
And let's not forget the engine gets through hydrogen rather quicker than it does petrol: we burnt 30 quid's worth in 60 miles, at least double what it would have cost in petrol.
But this is the prize: when petrol is flowing through its combustion chambers, the Hydrogen 7 (as BMW calls it) emits 332 grams of CO2 for every kilometre covered; switch to hydrogen and that figure falls to an utterly staggering 5.2g/km.
And it's not at all bad to drive: the performance is actually very similar to that of a diesel 730d and while the engine is notably less refined when accelerating hard on hydrogen (a symptom of the fact that hydrogen burns ten times more quickly than petrol), at a part-throttle cruise, you can barely tell the difference between them.
I drove it in and around Berlin until we were nearly out of hydrogen and thoroughly enjoyed the drive and appreciated the efforts BMW was making to find a way of making a car both environmentally clean, yet still worth pedalling.
Most impressively of all, or so it seemed, BMW told us it was going to make 100 Hydrogen 7s and let them loose on the public next year.
