Two years after the release of the original Hydrogen 7 ultra-clean limo, BMW has taken the wraps off a new ‘mono-fuel’ version that unlike the previous car, which had dual-fuel capability, is strictly limited to running on hydrogen. Also, the new car has almost zero-emissions, is more economical, has more power under the hood and is kinder to the environment than its predecessor. Perhaps the most important news is that the new mono-fuel 7-series isn't just a pipe dream either - the model presented was a demonstration production vehicle that will be delivered to customers on a trial basis.

The battle between different alternative-fuel technologies has begun in earnest, with electric, hydrogen, fuel cell and biofuel vehicles all making it difficult to predict which technology will gain supremacy on the fuel station forecourt - but the BMW does have one little extra thing going for it:

Thomas Wallner, a mechanical engineer, explains "the car's engine actively cleans the air" and that "testing shows that the Hydrogen 7's V12 engine actually shows emissions levels for certain gases that are cleaner than the ambient air that comes into the car's engine."

Other carmakers question BMW’s decision to develop combustion engines that run on hydrogen but BMW believes the technology serves as a stepping stone to the eventual adoption of a full hydrogen society where internal combustion engines could be replaced with fuel cell technology.