The host of modern hybrids to be found today are often partly powered by what their manufacturers call Atkinson Cycle engines.
The truth is that none of them are true Atkinsons, primarily because the stroke of the engine is constant across all four cycles. Trick valve timing simulates Atkinson behaviour, but only to a point. True Atkinsons have shorter intake and compression strokes than power and exhaust. Honda has devised an ingenious solution, but as yet is only offering it on their small lawnmower engines.