some_other_dave.... I really do understand that optimum fuel efficiency is the some of everything going on at the time, thats why I'm transplanting a 1.6 out of a german box into a much more stream line civic hb... but all things being equal. a 1.9l TDI will get 25% better fuel economy than a 1.6 TD at 1800 rpms. Thats what I'm getting at and thats what I'm looking for. If we had a list of ever engine and their respective optimum fuel efficiency, you could literally "pick out" the very best engine for you application, then take care of all the other considerations knowing that your starting with a strong base.
