The follow is a list of thing I keep in my car in a case:
→ 1 Plastic Crate with a Lid ($1 at a dollar store)
→ 2 in 1 Collar and Leash (3x)
→ Small Carabiner Hook - for securing dogs in the car when you don't have a crate
→ Hand Sanitizer - They're dog's, it happens
→ Gloves (Latex and Rubber) - protect yourself from animal to human ailments.
→ Shower Curtain - great for laying out under crates to protect your car from spills.
Additional Items in the car for planned transports
→ Queen Sized Sheet - to cover the back of the car
→ A Transport Binder - a very helpful binder!