Germany gets mighty cold and they have been making diesels for a very long time. Also, FIAT has been making diesels for their cars and commercial vehicles since the 60's. I doubt there would be a learning curve. Diesels are, by their nature, reliable and durable. I can only think of the converted Chevy 350 diesels when trying to recall bad diesel engines. In the cold, fuel gelling is the main problem and that has been solved with additives and heated tanks. The biggest problem I can see for diesels in cars and light truck applications is how efficient gas engines have become in the last 3-5 years. Do you really think it's worth 50¢ a gallon more for diesel engines if the mpg difference is only 2 or 3 mpg? I love diesels, I am(was) a diesel/heavy mechanics tech and I advocated for diesel engines for a long time. But the time of the diesel may be ending with the new efficiency of gas engines. There is torque benefits, but not so much as to make a big difference compared with modern gas engines. We will see a few smaller diesels, but it will not become common.