Rants on the topic of car camping
Conventional sleeping bags that zip up around your chest are one option. Mummy style sleeping bags are another option, and they can zip up and around your head. You can get a sleeping bag that suits your needs as far as temperature range, material and color criteria. Padding or mats for underneath your sleeping bag are also good to have. You can get anything from a foam egg crate style pad to a blow up mattress, depending on your needs.