I just took this off a tinting website
"Depending on your selection of tint, up to 65% of the Sun's total energy can be reflected away from your vehicle. If your vehicle is fitted with air-conditioning this should provide savings on your fuel and running costs. Not only that but tinting can reduce interior fading and help maintain the value of your vehicle."
More info:
Increased Privacy
Window tinting provides you with improved privacy depending on your selected shade of tint. However please bear in mind the current UK law which states:
"The front passenger and driver side window can only be tinted no less than 70%. Rear windows can be treated in any shade of tint. Windscreens must be clear from tinting apart from a 6" strip across the top."
Safety
In the event of a broken window, tinting film protects the occupants of the vehicle from flying glass by holding shattered glass in place. All our tints provide you with this protection. Furthermore, all our tints offer 98% UV light rejection.