Any Of These Pics Calendar-Worthy?

[blueskana]

If its right at your back the car's lines and color will be washed out and flat. It will be hard to not overexpose and you'll get more hot spots where the light is basically shining directly off of the paint into the lens. Off to one side or the other will allow you to pick up on the shape/lines and get rid of some of the glare. Fill-flash is especially usefull if the light is behind the subject and/or its a bright day. It won't take much light from the flash to catch and highlight off of the cars paint. Depending on how strong your flash is will dictate how far away you can be and get the desired effect. I would use a tripod as well, even with plenty of light. Depending on how limited your exposure range is, some camera shake, indescernable to you, may be effecting clarity/sharpness.
Best of luck, and nice car.