What is the best thing that I can buy and use to clear up my convertible top windows (the plastic) as best as possible?
Is the "cloudy" part usually the greatest on the inside, the outside, or pretty much both inside and out?
Thanks.

 

I use Plastix by Meguiar's both inside and out. Also use their Quick Detailer on the outside.

 

I also am a fan of Meguiar's Plast-X. It does a great job on a multitude of plastic problems. It comes in a bottle and claims to contain "micro abrasives. As well as the rear window on the SL, I tried it on the plastic headlights of my mom's Ford, and it worked better than I thought it would.
There is another product called Plexus which is commonly used on aircraft windshields, which is an aerosol, and seems somewhat gentler- non-abrasive. I use it on the windshield of my GoldWing, with much success.
Unfortunately, my rear window was too far gone to save, and a new top is en-route. The previous owner didn't love the car like we do.
Regards,
Perry