Good news , good news fellows
You can do this by yourself in Split Screen Mode with 2 controllers.
1) Go to Multi-player mode and choose Split Screen.
2) Have player 2 press start and pick a driver and player 1 does the same.
3) Select Race Now
4) Pick the track you need to get under lap time.
5) Make these settings adjustments
Tire Wear & Fuel: On
Caution Flags: On
6) Start race
7) Take controller #2 and press & hold
button at the drop off the green flag and player #2 will go in reverse and bring out the caution.
8) Rinse & Repeat 2 more times to end the race and in the end results you should have player #1 (PRIMARY) win the race and have a lap time of --.--.--
9) Now exit to garage & go into single player mode & select Race Now & go to the track you just boosted by yoruself & double check to see if you got your Star for getting under the required lap time (AND IT SHOULD BE THERE)
10) Now just reapeat the whole process for the rest of the tracks and you should knock this out in no time at all. After each race from now on use a spreed sheet to check off tracks completed. After you boost each race there is no need to exit to main menu , just simply select a new track from here until all have been done
Hope this helps everybody....
EDIT #1: There are reports of some short tracks that this trick does not work for , so far 2 of them are Dover & Richmond. If anybody finds that another track will not work by doing this trick please post it & I'll update this post to help others. But be honest & give it a fair chance for the trick to work before posting that it doesn't.
EDIT #2: I went back through every track on a different account for you guys to be sure of what would work & what wouldn't , so this list is my what I've come up with thus far... Imput in still welcomed.
Credit for helping in confriming tracks so far goes to...
Tracks this trick will not work on.
2)Richmond (this one is glitchy because I eventually got it to work , not sure how)
3)Bristol Day Track
4)Bristol Night Track