When we had a station wagon...my guy used to be in the *dog box* (what that area is called behind the back seats...even if ya dont own dogs *L*...well it is here anyway)

You can get safety anchor points put in that you secure you dog to with a harness....so if you are in an accident you poor dog doesnt go flying

You also should has as a minimum a cargo barrier to stop you dog from coming forward if excessive breaking is required

It is against the law here to leave any animal in an enclosed car no matter how long they are there for