Spawn an (e.g., a V4 or Inline-4 for standard cars) and place it on your chassis.
This is where the "UPD" keyword becomes relevant. If an old ACF 2.0 dupe breaks in ACF 4.0, here is how to fix it: gmod acf car dupe upd
Use the to reset the physical properties and weight of the tires. Where to Find Valid, Working ACF Dupes Spawn an (e