I drive with Sam loose in the car, but with his harness and leash on. He usually wants to ride in my lap, and help steer. I am sure it is dangerous, but he wails and whines in the carrier. I also have a litter box in the car, which he always uses.
I was going home one dark evening just before Christmas. I spotted a RIDE police check up ahead (where they stop every car, and check that you haven't been drinking). I figured they would frown on driving with a big cat in your lap, so I hurridly shoved Sam in the back seat. However, by the time I was stopped, and rolling down the window, he was back, and when the cop leaned down to look in the window and ask me the questions, Sam had his paws on the window frame and popped his head out the window and sniffed the cop's nose.
The cop said, "cute cat", laughed, and walked away.
I think that when the policeman said, have you had any alcohol to drink this evening, Sam heard, do you have any cats in this car?