Hello,
that's would be awesome to have the possibility to tweak the performance of the vehicle through the script. Being able to change rpm max, rpm, fuel capacity, gears, etc...
That's would give us a way to add a more realistic vehicle, if the vehicle has traveled a lot of distance, his performance decreases etc...
Or if he has some wheel ruined, he could not have the same performance. And much more other applications.
Or, for creator of vehicles, if they want to change directly the parameter of the vehicle, instead to repack an addon just for changing a simple value.