I think it would be cool to allow us to do engine swaps, upgrades, drivetrain swaps, etc. in game itself. For example, I could take the hard-to control Civetta Bolide, give it some handling upgrades, and swap out the RWD drivetrain for an AWD one in game itself without having to modify the individual files.
I myself like moddifying all the files, since (to me anyways) it's more fun searching all the things you need to change in order for your car to be AWD than just clicking a button. Than again, I'm more of a DIY person anyways, so that would explain it.
I'm sure there will be something like this in the finished version but for the foreseeable future you can just edit the files or use the different engines they have available for most vehicles.
