I have had my 2013 535i for months now, and I have been afraid to wash it. Yup, because it is a non-metallic black and the second I wash and dry this baby, I will have paint swirls.
YIKES - a black BMW and months w/o a wash!! It's surely got a load of crud on the paint that you can't even see BUT you may feel. Whatever you decide to wash it with be sure to flood the paint with loads of water to loosen any of that crud before you grind it into the paint with a wash and dry!
What soap should I buy? What should I buy to put the soap on the car (sponge)? What should I use to dry the car (I have heard that the "Absorber" chamois is the best)?
SOAP: Most any commercially available auto soap is OK. PepBoys, Wal-Mart, Target, etc. for sure. Some are sold as wash-polish-wax miracle combo products. Don't think of them as a replacement for a real polish-wax job.
SPONGE = NO NO NO Even a GREAT open cell sponge will transport dirt and thus increase possibility of paint damage.
IMHO a microfiber mit is one of the best - I use a "FOAM GUN" first to lay a layer of auto soap over the car and let it sit for a few minutes and allow it to loosen any dirt on the surface. Then I hose it off - foam it again and then, working from the top down use a thick microfiber cloth and mit go over the paint.
"Absorber" chamois: NO NO NO !!! IMHO they are heavily marketed and one of the worst products ever foisted on the car cleaning public.
If you have a leaf blower I use it to first blow the water off a washed car then use another Microfiber or 100% thick cotton towel to finish the job.
Depending on how much muscle and time you have most of the (again) commercially available waxes would be fine - especially since you've delayed washing your BMW for months you probably won't have 5-6 hours to prep and wax your car. Maybe you should consider finding a local detailer who can take care of the hardest part of keeping your car clean. It may be worth the money for someone else to do a "minor" detail job 3-4 times a year.
PS - don't forget to wax your wheels!
I am quite afraid of trapped dirt found in whatever applicator/drying mechanism I use - causing swirls. I would like to be able to buy the goods at a PepBoys, and not have to order it.
What type of wax should I use? What type of applicator?