Performance index vs actual numbers

[El_Barto_inc]

Hello all.
Recently I went on upgrading spree and put parts on probably most of my cars and while doing so, I came across something that confuses me, namely lunch and acceleration vs times 0-97 kph and 0-161 kph. Most upgrades consisted of race gearbox on AWD and when switching from stock to race many cars launch and acceleration index dropped significantly, even tho I get better numbers on 0- xx/xxx times (after adjusting the ratios ofc). Can anyone explain me that?

Second thing is with this weeks trial and playing with different cars.
Here is my first choice Lotus Elan:

but Lotus Exige has worse index, even tho its acceleration numbers are better

I’m kinda confused here.

[MyGamingID]

It’s because the ratings are all pre-tune. AWD swaps have really long gears, resulting in worse launch and accel ratings. You can tune gears to beat the sport transmission in actual performance, but the ratings will never change.