This might be on purpose.

I knew a guy who wanted his car to look like a rolling pile of rust on the outside, as if the car had been left to rot outside for years, to look "authentic", but the underpinnings were perfectly sound and the engine was a modern, fuel-injected, computer-controlled unit. So he had his car spray-painted over the rust and the grime with some sort of protective coating, so that he would look permanently old but never degrade further.