Car camping spots are roughly 20x20 feet, but that space includes where your car parks, so it’s more like 13x20 of camping space to the side of the car. Check out this picture for a convenient look at cars lined up in their campsites. Note the sedan to the right, that's an empty campsite next to that car.
RV spots are 20x50 feet. You may bring a separate "companion car" with your RV to fit in that space as well if you would like, but you will need a car camping pass WITH the RV pass, and this extra car must arrive at the same time as the RV. Cars/trucks towing an RV are considered a part of the the "RV" and do not need an extra pass.