Just bought a metallic pearl black Megane Coupe, and honestly it's not been washed in 6years. I've done the old drop-in car spray number on it and there is still a thick layer of scrud on it! What do y'all recommend is the best way to scrub it up properly?
some kind of bug / tar / road salt remover. let it soak in a few minutes. You can use a sponge on that while its wet.
as long as you have no abrasive particles on the paint a suitable polish/cleaner may be the best.
WD-4O is great too.