I sprayed just the interior including the doors, roof, quarters, and trunk. I will probably paint over the trunk to give it the original look. I put two thick coats of the SC (sound control) and one thick coat of the ceramic insulator on. They recommended buying two buckets of the SC and three of the ceramic insulator to do a midsized car. I would agree if you going to be able to spray the under carriage. With what I did, I had about a half bucket of SC and one full bucket of the ceramic insulator left over.