You just got your car washed, but the stubborn, ugly winter sludge above the tire well didn’t budge. The fix: Spread a thin layer of mayonnaise over the grime. After a few minutes, wipe it away with a soft . The acid in the mayonnaise will break down the dirt while the oil softens it, making it easy to wipe away. Don’t worry, the mayo’s ingredients won’t harm your car’s finish.