I moved from Los Angeles back to KC with 2 cats. In the back seat I put the litter box facing a single door small dog crate so they could sleep in one and poop in the other and not get out to roam in the car. No problem, I thought, great idea, right? Their own little condo. Well......my female cat immediately plopped herself in the litter box hissing at her brother who stayed in the cage with the blankets, toys, water and treats. But, they stayed in the back and all was fine. Good luck!
So sweet and so CAT like behavior!!! lol. I had something similar happen and I just shook my head and as you said they stayed back there—one in the nice cuddley cat carrier and the other in the cat box cat carrier. Too each his own I guess. Never a dull moment unless they’re sleeping of course.
After two days I bet that was a pleasant smelling car.
AND they dock you if you smoke in a car but NO questions about cats doing their do in a car. Go figure