Hip or shoulder holster? If you have a CHP, no problem with potential seatbelt concealment issue.
We tried to get the General Assembly to join the 16 states which don't require a permit to carry concealed in cars - the Senate changed the exception to a locked glovebox, then the Gov. vetoed it. So much for privacy and safety.
I hate to tell non-permit holders to levae a gun on the seat to be sure you are not accused of concealing...but what else can you do? Maybe make a special holster mounted in the car?