Cleaning Cars with Pure Water

You think the 7 gpm 12v pump will have enough power? It only puts out 60psi. I guess I could run some 3/8" hose to a short wand and connect a 2gpm 40° tip to that, but I wonder how much umpf it will have.

If I run pure water through my HP pump and 250’ of steel braided line, won’t it pick up impurities?