So, um, I'm not -entirely- sure if this is the right place for it, but... Weren't diesel engines meant to be a part of version 9? Are they still going to be implemented before the game is finished, or has it been decided that they'll be a post-release thing? Please don't tell me they won't be in at all!
lol Diesel Ted (totally unrelated). But Yes. Diesel was planned sooner than v9 - but like hangars, have been set aside at the moment. Wasn't it like... v7-v7.5?
Diesel suggests multiple forms of resources; which simply aren't in the game yet. :)
Diesel engines have already been considered. I'm guessing Zark's saving them for an expansion due to their complexity.