Bought a brand-new black Tacoma 4x4 Xcab SR5 in '99, and only washed it regularly and applied Turtle Wax Emerald Series...no polish, no prep. After one winter (including using the brush at self washing bays), there were swirls on the whole truck, grit all over the rocker panels which I never took off and my non-clearcoated polished aluminum rims were also destroyed!!!
Damn if I knew then what I know now. I treat my '91 Yota XCab like I should have with the '99.