^+1
try setting your F stop around 3-5 depending on the distance from your car. I have a lens that will go down as low as f1.4 but I basically never use it that low, nothing is in focus.
Try backing up a bit and using a lower f stop, that will keep just the car in focus. Use your zoom if necessary.
At the opposite end of the spectrum use an f stop in the low teens for keeping everything in focus (depends on the lens).
Here is a shot I took w/ a shutter speed around 10 seconds w/ a high f-stop. Just about everything is sharp and in focus.
