Unless you get the really expensive stuff, you'll have to replace it on a regular basis, since it scratches so easily.

If it's a 100% race car that will never be put back on the street, you can gut all the side window mechanism out and install the lexan in place in the permanantly UP position.

Personally, I think it's too much of a PITA to fool with for most cars.

Good Luck!
[addsig]