BMW Launched the car it calls the Hydrogen 7 at a British golf tournament - then drove it in the London-to-Brighton rally to back up claims that it's the world's first hydrogen-powered, emissions-free luxury saloon.
Later, it took the Hydrogen 7 to the London Science Museum to join a fleet of low-emission and zero-emission cars.
"Hydrogen 7 marks yet another step towards hydrogen-powered cars becoming an everyday reality," says John Hollis, BMW head of industrial affairs. "Zero emission motoring is no longer a dream and this car proves the technology isn't as far away as some sceptics think.
"We want to kick-start the debate about the future of personal mobility and the importance of hydrogen as the definitive fuel.
"The opinions of politicians and other influencers are important in driving this forward to ensure that hydrogen-power comes to fruition as soon as possible."
The Hydrogen 7 is based on the existing 7-Series and comes with an internal combustion engine capable of running on hydrogen or petrol.
In hydrogen mode the car emits nothing more than water vapour.
Powered by a 195kW (260bhp) 12-cylinder engine, the Hydrogen 7 accelerates from zero to 100km/h in 9.5 seconds before going on to an electronically-limited 230km/h top speed.
The dual-fuel engine allows the driver to switch from hydrogen to conventional petrol power at the press of a steering wheel-mounted button.
The dual power technology means the car has a cruising range in excess of 200km in the hydrogen mode with a further 500km under petrol power.
The Hydrogen 7 has a 74-litre petrol tank and another tank that holds 8kg of liquid hydrogen stored at -253C.
Such flexibility, says BMW, means the driver is able to use the vehicle at all times, even when the nearest hydrogen filling station is out of range.
Engine power and torque in the Hydrogen 7 are exactly the same in hydrogen or petrol mode and the driver can switch between the two without any effect on performance.