I've also got a "moderately road rage husband" in the driver's seat cursing and exclaiming at other drivers, and it is immensely irritating for the passenger (me) - because he seems less inclined to do that when there are others in the car e.g. his new daughter-in-law! Which of course I do point out.
So - I've told him that given that it increases the risk of heart attacks and that he has had one already! - that I think there's a risk that he may have one while driving, so next road trip I'll fly/train it to wherever we are going and see him there (not wanting to miss out on the holiday LOL).
He is so critical of other drivers, that I no longer drive when we're together, as I can sense his silent criticism of my driving.
Otherwise, I quite like having him as a husband!