How do the hydrogen Mazdas work?

These are not fuel cell cars. The hydrogen is, instead, burnt as normal within adapted versions of the internal combustion engine that powers the petrol RX-8.

The hydrogen, which has less energy by volume than petrol or diesel, is carried in large, highly pressurised tanks that rob the RX-8 and Premacy of much of their boot space.

Hydrogen releases no CO2 when it combusts, the main byproduct being water, although a tiny amount of nitrous oxides (NOx) are also released.

A fuel cell using hydrogen produces no NOx, and more energy, but Mazda has used traditional engines, since the manufacturing cost is far lower.

Click here to see a diagram of the Premacy's internal set-up.