My favorite cat that traveled so well in his crate disappeared and I rescued a cat at the shelter = less than one year old but not really a kitten. She hates the crate and howls I have seen some...
I've got a cat bed, along with a big basket for another cat, on the dashboard of the moho. They like to get up there and sleep or watch the traffic as we're driving down the road. In your case, I see that you have a 5er. Could you leave the cat in there instead? She'd have her bed, cat food/water and litter box.