Advanced Engine bits..
Selection of what type of belt/chain that runs your camshaft since, a chain would considerbly last longer than a belt, but inquire more weight at a higher cost of maintaince..
Selection of types of sleves in blocks ( this includes ALL Blocks not just aluminum.. )
Selection of pistons. Its nice that I can select the material that it is made out of, but a pistons head shape actually helps it aquire many things, such as how fast it scavanges its cylinders.. etc.
a selection of oil. Certain oil would affect parts life, along with what type of weather it could operate in.
Selection of camshaft gear material, do I want it to be cast ? or aluminum ~_^! I prolly overlooked that one and it is implemented.. ( have to check)
Selection of cooling gear, such as radiators, fans... these VASTLY affect a engines life...
Selection of spark plugs, as these are very important... since I can control how hot they are, or cold.. as well as how many per cylinder, as I do know a few cars have dual spark plug systems, a ford ranger is just to name one.. for a real life reference
This is just a small list of what my mind contains for engine bits.. I love engines, its my passion, this game is so far so awesome, and I've already preordered ;...;