To be honest I somewhat aggree with edgfactors post. Don't get me wrong, fantastic little game and loving it too.
I would like to see more indepth development of parts. Currently we have 5 levels to put in an upgraded stat to make what ever it is you are making. Now, I am not clued up on rules on componants but take brakes for example:
I imagine there is a rule on disc diameter, as in the disc connot be any larger than say 30cm in diameter to fit to a ERS car (this is all hypothetical) so when it comes to desgining your next disc upgrade you could have the option of making the disc diameter bigger than the rule book but then will have the braking stats increased BUT also have the rule breaking stat increased too. Sub options for brakes could be material used, carbon, ceramic etc. Pads, callipers etc. All this costs money so part design is based on what you can afford, how much you're willing to risk and actually have an input in performance increase etc instead of the set stats yolu get with the current way.
just my thoughts on it.