Since you will be car camping it is a lot more forgiving and dont be afraid to over pack if you have the room since you dont have to worry about taking only what you can carry.....My advice is to get a good blow up pad and a sleeping bag.....I think a 20 degree bag is a good all around bag you can use all 4 seasons unless you plan on winter winter camping (10 degrees or below at night)....You can always layer up when you go to sleep.....Beanie/gloves are a given and sleep with the beanie on if you get cold....Down jacket if you have one....Like mentioned above thermal base layers are awesome.....And I would only use those at night when sleeping or when the sun goes down to help keep them clean for the whole trip.....A good wind breaker jacket is nice if you have one and if its big enough to go over top of your down jacket you will be plenty warm standing around the fire.....Dont go over board on layering up with socks (only need one good pair) or clothes at night as that can actually work against you and cut off blood flow which will make you colder....If you can layer correctly you will be surprised at how little you actually need....Another thing you can do to keep the feet warm at night is put some extra clothes down at the feet of your sleeping bag to help provide some extra insulation from the outside of the bag....It helps a lot.
2 years ago I went on a backpacking/snowshoe trip with a buddy and it got down to 8 degrees at night and I was warm with a 20 degree bag....All I had on was a good base layer (top/bottom), pants, fleece jacket, down jacket and my wind breaker (non-insulated) in that order as well....That is what I wore at night outside without a fire as everything was to wet....I slept in my thermals, down vest and beanie but I also sleep warm and enjoy the cold.