THE light drizzle at the launch of the BMW Hydrogen 7 in Singapore this week was a fitting welcome for the German automaker's showcase of its eco-friendly credentials. After all, this is a car that touts water vapour as its only emission.

The H7 is a bi-fuel version of the 7 Series limousine and BMW's answer to sustainable motoring. As part of a world tour, five of these cars are in Singapore until March 23 at a purpose-built pavilion behind Parkview Square.

'With a growing focus on the search for sustainable and environmentally friendly fuels in Singapore, and its prominent position as a research and development hub, we believe this is an excellent opportunity to engage the public on the latest developments in hydrogen combustion technology - one which the BMW Group has been pioneering,' says Roland Krueger, managing director of BMW Asia.

During the event, invited VIPs will be chauffeured around in the H7 to experience how its V12 engine has been adapted to run on either petrol or liquid hydrogen. When operating on the latter, BMW says the only emission is water vapour.

Outwardly, the H7 doesn't look much different from any other long-wheelbase 7 Series model - except that it has two filler flaps on its right rear pillar. The one that looks more high-tech connects to a special tank in the boot that stores eight kg of liquid hydrogen at minus 253 degrees Celsius.

In the cabin, everything is pretty much the same except for a button on the multi-function steering wheel marked H2. Press this and a metallic double click from somewhere behind indicates that a valve has been activated to release hydrogen from the tank to the engine.

At normal speeds the sound level from the engine remains unchanged when operating in this new mode. But unlike a normal petrol-engine 760Li with an output of 445 hp, the H7 has had its six-litre V12 engine detuned to just 260 hp, so its performance in gasoline and hydrogen modes is evenly matched.

The car's 2.2 tonne kerb weight has also risen by more than 200 kg because of the hydrogen tank. As a result, acceleration from zero to 100 kmh is down from 5.6 seconds to 9.5 seconds.

However, 260 horses is still a lot and sitting in an H7 is as comfortable and luxurious as sitting in any long-wheelbase 7 Series. The hydrogen also adds another 220 km to the H7's range.

It's fast, it's big and it's clean. So what's not to like about the H7? Oh, except that you need a ready supply of liquid hydrogen and you'll have to wait until at least 2018 to buy one. That's because BMW doesn't expect the technology to be viable for another 10-15 years. Just in time for the next oil crisis.

The BMW CleanEnergy Pavilion at the corner of Ophir and Beach roads is open from 9am-6pm daily until March 23. Admission is free.

This article was first published in The Business Times on Mar 8, 2008.