since the track updates when I play single player the car i’m driving at the time bogs down and does not move even though I have the no traction and stm mod on with -15% grip so all cars just drive into the back of me so the car is ready for the scrapheap before turn 1 as I have everything off and full damage.
TIA
If you’re using manual with clutch it means your first gear is too long. Shorten the first gear and smooth out the remaing ones to optimise acceleration and top end speed. 
Sometimes the high end racecar will bog on the line. Like said, shorten first gear. If it’s a showdown and you cant, switch to manual.
I only use manual and the gearing was fine before the update its only starting happening since the last update even if I put the gears down for acceleration it does the same thing and its not just 1 car its all cars . and the #28 Honda indy always spun up to 4th gear. its just strange that its only just started happening.
here is a video of what I mean start 1 ok then restart and it doesn’t pull away with the exact same setup on both
This has to do with the rev limiter. When at full throttle, the engine revs up, then is cut off for a split second when it hits the limiter. The difference between your two starts is simple:
First start - Engine was revving up, allowing full power to reach the wheels.
Second start - Engine cutoff due to rev limiter, meaning it could not reach the revs possible for a clean launch.
Shortening first gear alleviates this problem because it does not allow the revs to drop below the “stall” level when bouncing off the limiter.
Simple - stalled it! This happens to me also, I’ll try the gearing adjustment, thanks