Industry rumours suggest that Mazda is planning a revolutionary diesel rotary engine for the next RX-8 coupé - a first for a production car.
The Japanese firm used a petrol 'wankel' rotary engine in the outgoing RX-8 (pictured) and in former models including the RX-7. The coupé is distinctive in that respect, but it's often criticised for high fuel and oil consumption.
Mazda is now working on a replacement that will keep the rotary format but run on diesel. Rolls-Royce unveiled a prototype diesel wankel engine in 1970, but it was never used in a production vehicle.
Details of the new engine are sketchy, but Mazda wants it to be powerful and much cleaner and more frugal than the outgoing car.
The final version of the RX-8, the R3, develops 228bhp but only has 155lb.ft of torque and emits 299g/km of CO2. Mazda's priorities for the newcomer are to boost torque and to lower emissions. A 0-62mph time of less than five seconds is also rumoured.
According to insiders, the reason that Mazda hasn't ditched the engine layout is because demand is still high for a rotary-engined sports car in the USA. The new RX-8 is expected in 2012.