Never get undercoating on a car. In fact, never get any of those dealer added things like undercoating, paint sealent. All they are is pure profit for the dealer. If they do anything they will most likely apply the rustproofing improperly and that will accelerate rusting. Actually, the only vehicle I have EVER purchased where they didnt try to sell me those add ons was my Lexus. They're honest I guess.