I use tripod cases for all of my tripods when carrying them in the back of my 4Runner. The case protects the tripod from impact damage, which is more likely when driving on rough backcountry roads. I also use a tripod case on my river trips to protect the tripod and head from impact damage that could occur as a result of the baggage load shifting in the rafts when going through the rapids.
I've tested many different brands of tripods bags and cases, and I haven't found any that are nearly as well made as these from Really Right Stuff. They feature full-length dual zippers, protective 0.5" closed-cell foam padding throughout, and a covered ID pocket on the outside of the case. There is an exterior zip pocket and an interior zip mesh pocket under the lid for carrying tripod accessories. The case also features handles and an adjustable shoulder strap.