Join Date: Apr 2007
Location: Brisbane, Australia
You can cup a polarizer over your lens but be careful of scratching the filter on the lens barrel.
A polarizer works on one plane. If you remove reflections from the side of the car, they will remain on the windscreen, or vice versa, but well worth it.
No special "digital" polarizer is required.
Be warned they suck up light, 2 f.stops worth, and work best at 90' to the light source, in your case the sun. With the sun directly behind you, it won't work at all. But hey, that's the worst place for the sun to be anyway.
I'm a pro photographer and have one on at most times. They dramatically improve almost all outdoor photography by producing rich, saturated colors. Everyone should have one!