Send the plates to VFX dept ?
Depends how bad they are.
do a luma key for them
put a window round each one and track the spot. 1 window per spot
Expand your matte
grade to be same red (though you wont get the shading/reflectance properties of the paint)
depending on movement could also try offsetting in the x or y ie clone
but that depends on the cars movement
still should be simple.
S