That's tricky. The 'light' version certainly helped also with different applications other than just books and screens and I used them in the car regularly, but the higher ones are useless for that because I can't keep all of the interior bits of the car in focus at the same time as the outside world so I drive without glasses, it also significantly reduces my dead angles due to improved peripheral vision.

So there may very well be more than one effect at work here. I can't really see the instrument cluster in the car but I know it by heart so it's not a problem and speed I can do by ear and get it well within the margin of error for speeding tickets.

I should probably get re-tested and maybe try bi-focals, but with the amount of driving I do right now I don't need to bother, the car is used so little I have it on a trickle charger to prevent the battery from going dead.