The cover has saved me from repairing several "guaranteed" scratches (like that time the rake fell off the garage wall and slid all the way along the car
). If the cover wasn't on, all the wax/glaze/polish I could layer on wouldn't have made a difference...
You do need to "clean" the car every time before you put on the cover, but this doesn't necessarily mean "wash". I do the once over with the California Duster and if I'm really fanatic use the lint roller on the top and then put on the cover. If I let it go too far then I'm stuck washing again before I use the cover and the car stays uncovered until then.
There is no "requirement" for a cover, if it suits your temperament and situation then it is useful. If not, that's fine too. Same thing for garage vs. outdoors. If mine was a daily driver I doubt I'd be using the cover myself.
Hlee8, I got my Noah cover from "Tweeks" (now Mid America Motorworks) -
www.mamotorworks.com . They carry several types of covers from US $50 to $200 for the Boxster. The Noah is their top rated cover, but there's plenty of other good ones; the Porsche cover has a much nicer logo on it than mine
.