Lotus have just released details of the variable compression, 2 stroke petrol engine that needs no spark as it ignites like a diesel at most load conditions, but it also has a spark plug for when it needs it. The variable compression is impressive, as is the exhaust trapping valve. Meant to be 10% more fuel efficient than a comparable 4 stroke conventional engine.

Fuck me, a nice bit of engineering ... have a look and play with this interactive demo!

http://www.pistonheads.com/lotus/omnivore/