I have similar issues with a 30-year friendship as well.
I've had to back away from the friendship slowly, while maintaining the contact, as she is part of a larger group. No one else in the group does this to me except S., but as she and I were the first friends of the group, we are the most integral to the whole group.
As in your situation, S. triggers me as well.
We have had a couple of heated discussions about this, with S. apologizing, yet S. will do the same thing, months or years later. I simply sit there in silence, so everyone else just thinks I'm this nice, sweet person.
Not that your friend is an enemy of yours (or mine is), but I heard this quote recently, and I think it applies:
"When your enemies are making mistakes, don't interrupt them".
In other words, remain quiet and calm. Let your friend show who she is. When she's barking driving directions at you, let the others in the car hear her, while you just keep driving. Let her be heard by others, and she will show herself to be who she is.
Like you, I have a ton of other acquaintances, but not as many true friends. I have backed away so much from my friend S. in recent years that she's become more of an acquaintance than a friend, which is actually great, because it allows me to enjoy the rest of the group peacefully.
Just wanted you to know that I totally get where you're coming from.