A gravity fed HVLP gun will probably use 30 % less paint than a conventional syphon. Less waste, by far. PPG base coat uses 1:1 reducer/paint. Whatever you buy in paint will be doubled in volume by the reducer. One gallon of base added to 1 gallon of reducer would be enough to paint a huge car.3 coats should give you adequate coverage. Ist coat should be light 2nd and 3rd should be wet.Since PPG clear coat mixes 4:1 you will not get as much coverage as the base coat. I would not skimp on the clear coat. A gallon of each should be sufficient. If you buy an extra gallon of clear coat, bring back the unopened can if not needed. 3 coats of wet clear works great. Have fun.