I have to park outside in Pacific Northwest weather so it get's washed about 1-2 times a month. I know hand washing is the way to go but other life priorities get my time and energy.
So far I've managed to avoid significant noticeable swirls on my MGM by using the local auto wash chain with cloth based 'parts' that touch the car. And I splurge for the extra shine/carnuba(whatever) rinse, followed by a full MF wipe down to prevent spotting and such. Then once a year at a minimum, I take it for a full inside / outside detail including polish at a local detail shop.
Also, I always decline the dealer offer for car wash just in case they have some plastic 'thing' they want to use. ;-)
fwiw