Car sex

How to spice up car sex? We usually just do missionary, he eats me out, and I give him a blowjob. Sometimes I ride him but the back seats are small asf and the roof of the car isn’t high at all so I hit my head a lot. Any ideas on what to do? It doesn’t have to just be new positions, it can be other things too, for example I wanna bring my vibrator and experiment around with that. Any suggestions will be appreciated!