Hello,
Generally it’s not a good idea to change the scale of the actor blueprint with skeletal mesh in it. You will get the physics with unpredictable result. In the level blueprint and in the car blueprint there are a few functions that use the set actor transform which are return the actor scale to the 1,1,1. You can try to change these functions by yourself, at your risk, because the package doesn’t have this functionality.
Regards,