Personally, I wish the engine technology itself would improve. Lycoming and Continental have not improved in that department in a lotta years. If the powers to be would look at the induction system, for example, fuel economy, horsepower and torque could be increased so much that I think it would benefit everyone. (Except Big Oil). A while back there was an exhaust system developed that I couldn't believe the numbers on... Increase in everything except fuel consumption, at a cost of about $2500. If you really want to see how inefficient an airplane engine is, get a JPI analyzer and download the info and have a look. Continental engines are the worse as far as efficiency is concerned, but they do make a lot of power, if you have the $$.