How do I start as fast as the AI cars?

Solution 1:

You change gears earlier which means (for some dumb reason) you lag a bit while they are still accelerating in first, if you wait until the moment when the light turns green to floor it you will be changing gears at the same time (note: this is if you are using an automatic transmition) and thus you will be neck and neck with the lead cars. This takes a few tries to get right, there's a sweet spot that if you hit you can get off the line first.

Solution 2:

a) I also did the entire game and I came to the conclusion that there is no real way to get a perfect start! Just make adjustments to settings of your car to improve performance in terms of grip and acceleration.

No magic bullet this time! Unfortunately, you're not in Mario Kart.

Solution 3:

Try using 2nd gear instead of 1st gear when starting. It sometimes works.

I think the player's car inevitably has some delay between gear shifting, while hardcore AIs (miraculously) shift gears without that delay at all. You'll notice(in landrush or raid event) that AIs get ahead of you each time you shift gears...;;

In London rallycross stages, we might also have disadvantages in starting grid when we are placed "behind" on "dirty" "upslope" with less grip. You know, the 8th driver need to climb up more.