One rumour floating around at the moment is that the eventual Mazda RX-9 sports car may pack an H-Bomb under its bonnet.
According to these rumours, Mazda intends to use the technology behind the RX-8 Hydrogen RE to make the RX-9 into the flagship for an eventual range of dual-fuel Hydrogen-petrol powered cars (not forgetting the FCX), offering a 20 percent improvement on fuel efficiency and emissions as compared to a regular rotary engine.
Mazda's engineers apparently envisage the hydrogen component being used for day-to-day city driving, switching over to petrol for more spirited driving when desired.
Whether this engine will be the only option made available, is unknown. Rumours are good like that.
Beyond that, the usual suspicions for the RX-9 apply. Styled strongly on the lines of the Taiki concept, offered in both a manual and auto spec, and power put down at the rear wheels. We've touched on concepts a couple of times before, but nobody knows anything for certain at this point.