A incomplete list of the type of changes I make, if needed by any particular car.
Match wheel Track for physics, graphical and skid marks.
(The Zero point of a cars suspension is just with all the numbers in but before the car has been placed on the ground.)
Adjust body tilt(stance) so it is parallel to the ground at the zero point.
Apply an Aero angular offset as aero is done from the plane of the CoG points so is often not parallel to the ground.
Adjust the ground collider so the lowest point coincides with the lowest point of the car. If the car has a very uneven bottom profile it will often take more than one collider.
Adjust ride heights to match the collider above so at 0mm ride height at least one part of the car will be touching the ground. This means that if your ride heights are even your car will be parallel to the ground.
Adjust AI and Auto shift points and enable a working autoblip if needed. And remove unfair shift delays for non H-Shiter users.
(One of these particular cars seemed to have an incorrectly named tyre.)(and the Imp seems to have 4% more grip, I know not why?)
Rationalise files in the data folder, some aren't needed, some are identical and have their references changed to point to a single copy.
Using the rational that all cars should be able to lock up their brakes at least once, I adjust brake.ini to reflect so.
Adjust the UI to tell the truth if needed. Rationalise Tags.
FFS set STEER_ASSIST back to 1, and remove [RULES] MIN_HEIGHT=, as it buggers the physics.
Rationalise the pitstop times.
Remake the car colliders to be more collision friendly.(mostly to have vertical sides)
Do due diligence on the auto generated LODs, whilst surprisingly good I'm not a fan of the auto generation.
Change chrome to avoid reflecting anything from outside the car, remove stuff the race car wouldn't have, add stuff the race care would have.
And a bunch of other stuff as you can always find something wrong if you look hard enough.