Ok guys, finally I've got one suggestion from NotoriousA. So I've got to apply two custom routes to the non-bridge road side.
So it is the suggestion of NotoriousA:
A pic for my plan to apply routes.
The red circled opponents are the ones which will go to non-bridge road and green circled opponents will go from bridge jump.
Since, opponent 2 & 8 have already good routes, I wouldn't change them and as I want to apply my custom route and NotoriousA's route.
I'll apply them to two opponents of non-bridge, I'll apply my custom route to that Aston martin as it as its slippy car so it would go straight which will help it handle some of its speed.
And I'll apply NotoriousA's route to RSi because his route has to turn on full speed to hard which RSi can do easily as its good on taking hard turns and less slippy, Aston may crash into wall if it use that route.
Now the non-bridge side is being done almost.
I need suggestions for routes for bridge side as fast routes.
PS: The opponents can go through grass between the walls which just comes after bridge jump which is here.
So here's the grass route which I was talking about which AI can use in-game.
More progress soon.