Mercedes developing new fuel efficient engine

'DiesOtto' to achieve 40 mpg?

"Mercedes-Benz is working on a new kind of four-cylinder engine that combines features of petrol and diesel motors to generate 238 horsepower," while still achieving around 40 mpg in an S-Class type Mercedes.

"DiesOtto -- the name combines the German words for diesel and petrol engines -- envisions an engine with a displacement of only 1.8 liters, turbocharged for high performance and using petrol direct injection to boost efficiency."

"The idea is to use a spark plug to ignite the fuel/air mixture when starting the engine or at high speed. At low and medium speeds, however, the combustion process works more like that of a diesel engine, which does not use spark plugs," writes Reuters.