What are the best settings for car photography in sunlight?

I bought the Nikon D3000 a couple weeks ago mainly for car photography and I've tried some different settings to get that perfect picture but it's not really doing anything, but anyway i'm going to a car show this weekend and I'll be there from like 8 in the morning until about 4 or so in the afternoon and it's supposed to be sunny all day. I've heard that filters help with glare and stuff but do they really work and can you tell me some settings for the BEST pictures for the morning and afternoon when the sun is at the highest point.

I have the 18-55mm lens on now but I'm thinking of maybe buying the 55-200mm lens, do the different lenses make a difference quality wise?

A lens change is not going to do anything for you. Get a polarizer filter. This will take out excess glare and deepen the colors. However, a polarizer only works at certain angles to the sun. Just put it on the lens and adjust it to see if it helps. It will not hurt to leave it on the camera the whole time if it stays bright and sunny. You should also use a lens hood to help prevent glare from the sun. Unless you have a rubber hood that screws into the polarizer filter, you will have to remove the hood, adjust the filter, then replace the hood. Sometimes the best car shots are simply detail shots. Look for interesting lines and flow and characteristics of the cars rather than always trying to just take an overall shot of the entire vehicle. I suggest you use the A, aperture priority function of your camera and set the aperture to f8. This will put your lens at it's "sweet spot" for sharpness and give you more depth of field which you usually want with car photos. Take note of the shutter speed set by the camera. With the polarizer and f8 aperture, the shutter speed may get under 1/100. If it does, raise the ISO to 400.

Some examples:

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