Here are my thoughts on my own experience with driving while autistic. First, driving is scary. Unlike most teenagers, I did not look forward to getting my license. I remember my father saying that I'd get used to it, that the car would feel like an extension of me, driving would become as automatic as walking. Well, that was a problem! Had he not seen me walk lately? I still bump into people no less than 12 times a day, and that's when I'm really trying!
Amazingly, I have had very few incidents with automotive clumsiness. I attribute this mostly to being very aware of my attentional deficits and sometimes slow reaction times. I leave a distance between my car and the one in front of me through which two semi trucks could waltz if trucks could waltz. This is not to the liking of other drivers, who know that no rigs will be dancing through the streets and take advantage of the opportunity to cut in. No problem.
I don't answer the phone, drink coffee, look at the mail or even turn on the radio when I'm driving. I can do one thing at a time pretty well (like steering, shifting, attending to lights and traffic, if I think about it I'll stay home for a month).
I drive under the speed limit. I use my turn signal. I don't wear my seat belt. I don't change the oil on time. I do let the gas needle hover around "E". I do let papers, books, food containers, clothing and other junk take up permanent residence in the back seat (and the front) and even though I stopped smoking months ago, there are still cigarette butts in the ashtray.
Driving is something I need to do alone. I don't mind paying for gas, but explaining the rules about the radio, the windows, and the not-talking-while-I'm-trying-to-merge would wear me out in the first mile. The car is a private space, too, like the home. I can say the times tables out loud if I need to. If you want to go somewhere together, I might go along with that, on a good day, but first I'll need to ask you, "Can you drive?"