If you want to really strip the crap/dirt/aged look from white interior/exterior vinyl, I use 3M general purpose adhesive remover

Word of caution, once you start you have to finish as it really whitens the surface, use ONLY CLEAN WHITE RAGS, make sure you only wipe the vinyl surface,do a small area at a time, change out for a fresh rag as often as possible, don't saturate the area, don't stay in one area too long, give the cleaner time to evaporate and the vinyl time to recover, touch noting else when cleaning as you might smear that color into the white grain, keep it away from painted/dyed surfaces...


All the other "whitening" products pale in comparison


Mike