I've been travelling with my 10 yo female Zia for 3 years.
She rides in the 5er's walk-in bedroom closet where she has nice comfy blankets and plenty of room. Litter box nearby with food and water. I've tried her in a carrier in the truck but she hates that - she just howls. As far as I know in the 5er she just goes to sleep and never makes a peep. When we get to our destination her eyes always reveal she's been sleeping.
I don't keep her from getting outside; cats are curious creatures and I encourage that. We go for walks, no leash, and she stays pretty close to me. It took almost 2 years for me to really get comfortable with that. Sometimes she hides and really doesn't want to be found, but that's just how she is. I got used to it. She always comes home.
She knows when predators are around. She knows what coyote scat looks like. If I find that we're off to find a safer place. She's a smart little girl and having her as a travelling companion is wonderful.
I can't say all cats are this adaptable, or their owners, but that's how we roll.
