When I have a deeply engrossing unitary (I.e. not one of five tasks but one task for months) project at work I had better start commuting by train and cut out the driving. I have lost two cars by not doing that. Fortunately no one was hurt. One car I had towed to the work parking lot, and just never thought about it until some time after the project when it turned out the office just had it towed off as unknown junk. The project went well.
Oof, that's kind of scary. Sorry you experienced it, and glad nobody was hurt.
I had a workmate at a gamedev place I worked (so lots of deep technical challenges) who apparently regularly missed the motorway exit for work because he was thinking about what he was working on.
I guess the point is even if the distraction is 100% internal you should still do your best to pull yourself out and get your focus back on the road.
