I have a 1986 300e with 176,457 miles on it, and the paint looks brand new !!
I used to do detail work, pinstripes , window tint, car cleaning,etc.. I did alot of business around MB dealerships and learned alot about it. I will tell you what I have used, and it works like a charm.
1) I bought a orbital buffer at Home Depot ($29.99). This orbital buffer was made exclusivly for HD, so I dont know who made it. Al I know is that it turns 3500 rpm's, with a .08 amp motor. It works beautifully so far..(have only used it twice so far)If you buy a buffer/sander turning higher rpm's, you will have to be very careful as to not "burn" the paint.(this usually happens around crevices and humps). My buffer turns perfect speed , not too fast or too slow.
2) I bought Meguiar's "Car Polish", this gets out what is IN the paint, remember, polish gets out what is IN the paint, Wax only protects the paint ! After washing my car, I used the polish all over the car, and then wiped off with 100% terry cloth towels.
3) Last, I use Meguiars "High-Tech" yellow wax. This is a great wax, made with pure #1 Carnuba Wax , which I apply by hand, and then wait till dry, and wipe off. Make sure to really shake the bottle of wax, for the carnuba has settled at the bottom and just needs to be shaken. And thats it, it will work great for you too..