The French Company SMA have a 230hp diesel (based upon a renault unit) flying in a TB20 at the moment. This unit would also suit a Cessna 182.. .TBO is said to be around 3000hrs, with a fuel burn upto 50% less than the avgas equivalent (conti 0-470)+ fuel is red diesel or jet A costing around one fifth the price of avgas. Good news for light aviation all round.