TheViper is right about 3M Crystalline. After three years of the Colorado sun, I finally decided to add it, right before our 100 degree weekend. What a difference. Plus, it greatly reduces the laser-like glare off the front fenders when they catch the sun just right.
The shop that did it had two 3M installers out here for a month from SoCal. They were very well-versed in the Lotus. I knew right away my installer was for California when he said "Lotus...dude...your windshield's got
GAME"
Tom