There are many angles which you can take of the car - front, side, top down, bokeh shots etc etc and there is no one correct rule. All you need to do is to make sure that the shot works for you and your client so a few different angles will help. Do not I repeat do not forget to leave out the number plate in at least 1 of your photos.
You may also use the car as a prop for the group photo or as a foreground/background subject. I've included 2 photos here just to give you an example of the different ways to shoot a bridal car.
Hope this little tip helps.