O. M. F. G.
This achievement is legit so fucking ridiculous to get. The fastest route Ive found is in Financial so far and it takes 1 minute and 50ish seconds per every two cars delivered and I think I barely was able to achieve 100 cars in an hour and a half yesterday before I left for work...
Wait so this means I have 751 more cars to deliver and if it takes the 1:50 I timed earlier, that means that I will need to spend 22.9472222 hours getting this cars for this last achievement.....