I flew a Diamond DA40TDI with the Thielert Common Rail Diesel engine the other day, and I must say that I was impressed. Fuel costs are very low, and the performance, even on higher altitudes was quite good due to the turbo charged engine. The computerized flight control is very convenient, but needs some time to get used to. For example, the entire run-up check is just pushing one button.
If you are interested in details, the aircraft operating manual is available from www.diamond-air.at in pdf-format.
I am totally missing basics and clueless about airline flying!