I gave my MS it's first full wash and detail the other day. Overall, nothing really different than washing any other type of car, however, I did notice that a great deal areas of the car trap excess water.
Thus, for a proper detail, I suggest having some type of compressed air, or maybe a leaf-blower, to force out trapped water around the door seals, hatch seals, frunk seals, side mirror seals, tail-light seals, and especially around the front light seals. Also a clean wet high-quality shami or sham-wow, to collect the water as it runs out the seals. Finally a good quality clean microfiber cloth, and some commercial detailing spray (I use Mothers), to remove any water spots, etc. I also use a high-quality cleaner / polish / wax for any minor scratches, etc.
Being the wheels are also painted, they can be treated the same way.
Being a life-long Southern California resident, knowing how to wash and detail your ride can be a very rewarding experience. Otherwise, I suggest hiring a professional detailing service, if you really want to maintain the paint, and quality look of your MS!
Otherwise, if you trust your local car-wash... well, as the saying goes... Caveat emptor.