Mazda Miller-cycle rotary Mazda will follow up its Miller-cycle piston engine (expected this fall) with a Miller-cycle rotary. A Miller-cycle engine is characterized by its use of a greater expansion stroke than compression stroke, with its main advantage improved fuel economy.
The asymmetric expansion/compression is most easily achieved by using what would normally be a compression ratio so high that it would cause detonation with normal pump gasoline, but then effectively reducing that ratio by either limiting breathing (with an intake restriction or very short intake opening period), or by allowing some charge to back out of the cylinder because of a delayed intake closing.
Mazda is taking the latter approach with its Miller-cycle Wankel, using an undisclosed mechanism to vent charge from the Wankel's compression space. Because the company mentions reduced pumping losses at cruising speeds as one of the design's advantages, I would assume that the amount of charge vented varies with load, perhaps under the control of a fairly sophisticated throttle-by-wire system. In any case, don't expect to see the Miller Wankel until 1995 model year at the earliest.