Where you won’t fail to identify this Seven from an ordinary 760iL, however, is when lifting the bootlid. This is where BMW has accommodated the 165-litre aluminium tank necessary to store the liquid hydrogen for the engine, and that gives the car a 120-mile hydrogen range, on top of its 300-mile petrol range.
The Hydrogen 7 does have a boot, but it’s greatly reduced in size – and there’s four inches less legroom in the back than in any other long-wheelbase Seven – another compromise made for the hydrogen tank.
What's it like?
Once it’s started up, so well-insulated is this car’s engine that you really wouldn’t know it was turning over at all, let alone be able to identify the fuel it’s burning. On the road, it’s not the most convincing exponent of BMW’s "ultimate driving machine" philosophy, and that’s because it weighs 250kg more than standard car as well as being less powerful.
Performance is acceptable, though; 0-62mph taking just over nine seconds. Top speed is limited to 143mph. BMW’s real achievement here is one of refinement rather than outright performance. When running on hydrogen, the Hydrogen 7 delivers its power just as freely and responsively as it does on petrol – and that’s a considerable success when you consider that hydrogen burns 10 times as quickly as petrol, and is therefore much more difficult to control during combustion.
You can switch from one fuel to another while the engine is running at the touch of a button on the steering wheel; there’s a momentary interruption in drive, but nothing more intrusive than a gearchange might otherwise be. And although the engine takes on a more hard-edged induction note when it’s consuming hydrogen, it remains as refined as most diesel engines, even at high revs.
Should I buy one?
Well, you can’t. BMW is only making 100 Hydrogen 7s, and will retain ownership of every one. If you’re a forward-thinking captain of industry or an environmentally-aware celebrity, you might be offered the chance to lease one for a few months – but the rest of us will have to continue to drive fossil-fuelled cars for the time being.
That's not such a bad thing, of course, because only a handful of filling stations in continental Europe sell the liquefied hydrogen needed to run the car. Even if they did stock the right stuff, it'd cost you three times as much to run your BMW on it right now as it would ordinary unleaded. Worse still, since that hydrogen would probably be extracted from natural gas rather than from renewable sources, you'd actually be doing more harm to the environment by doing so than you would by burning the equivalent petrol in your tank.
Nevertheless, BMW should still be congratulated. The Hydrogen 7 is a fully homologated and type-approved production car; as such it's been put through every relevant crash and stress test, and proves that hydrogen-powered cars can be made safe for our roads, produced in the same factories as any other car, and can provide levels of performance and refinement that are within touching distance of their petrol-powered siblings.
The rest of the world may not be ready to accept it, but BMW certainly seems ready and able to make a near zero-emissions car.