With the recent announcement from Achates Power and Aramco Services to put a cutting-edge engine in the Ford-150, excitement is building that this might change the future gas powered vehicles. According to CNET,
"Achates' opposed piston engine is a two-cycle, 2.7-liter, three-cylinder with six pistons arranged in a pair per cylinder, working against each other rather than each piston in its own cylinder working against a head and valves. Achates controls the engine's response curve by modulating pressures through both a supercharger and a turbo instead of varying valve lift and timing. No spark plugs, either -- the Achates design uses compression ignition like a diesel, but runs on gasoline."
Read more here.