Originally Posted by LunaZ

Actually, it's not what it is. You have total control here... that's why you bought a DSLR intstead of a point-and-shoot.

Step One: Get out of Auto.
Set a lower, less noisy ISO than what Auto is going to choose for you. 100 is of course, ideal.
Aperture can be tricky with large objects like cars. Do you want the whole car to be in focus and sharp? Try a 5.6 or narrower.
Use the light meter at the bottom of the viewfinder to determine your shutter speed. Move the shutter speed faster of slower until the pointer sits in the center. With white cars, it can be tricky. Try to meter on something that's somewhere between the brightest white part of the car and the darkest black to get a good compromise. Then you can adjust exposure, shadows, highlights and contrast in post. Lightroom has a noise reduction slider that doesn't effect brightness.

In a pinch, any stable object can become a tripod. I've taken off my shoes and used them to cradle the camera for a low shot. Think like MacGuyver!