With the help of TheAutomanEmpire, I can present some interesting statistics for all races:

In a perfect All races (new player) run (considering the IL World Records) we could achieve a theory time of 1:12:55, which is another 4 minutes of timesave compared to the WR right now. My sum of best is a 1:14:58 which is still 2 minutes of timesave.

Disregarding the 6 seconds that are spent in every race transition where the camera shifts to the car and the game goes through the countdown phase, we only spend 36 seconds in total doing something else than driving (menuing, switching to next level, etc.)

Unless we will see new findings, I doubt we will ever see a 1:12, 1:13 or 1:14, but I wouldn't count out the possibility of a 1:15 if someone manages to string together an insane run.

You can view the calculation spreadsheet here: https://docs.google.com/spreadsheets/d/1JkVr0sdIjFmTT1NBNXxhXg5lxhhN-_lUqSR50uQwpuE/edit?usp=sharing

Note that above calculation is already outdated since a lot of minor improvements to individual levels have been made. Not doing the work, but I guess the theoretical limit should now be ~ mid 1:12.