pump your arm in the international sign for "toot toot", see what she does? If no reaction.... maybe get a kid to do it. Truckers always honked for me when I was a kid,
Hahaha! I'll make sure to do that next time she pulls this- something tells me she can drive better than me, it would also explain why she's such a great road trip cat.
We just drove her across the country and she just sat patiently in the back, arms crossed. Absorbing the sights.