How many Plasti Dip Gallons You need to Dip a FULL Car. The quantity of gallon you need to dip a full car really depends on the size of car, current car color and the final color you want to apply. If this is the first time you are dipping a whole car, or if you are using one of the lighter colors (white, orange, yellow and so forth), get yourself an extra gallon or two. You do not want to run out of Plasti Dip in middle of your project. PRODIP recommends 6-8 coats on a surface if you want the dip to peel properly.