Recently i've tried to level some cars with same weight x power x torque... but it don't work well with weird GT physics. Impossible to match performance.
So
@m0b1us writen above seems to work . Normally , when i don't have problem with consumption involved , i check all the options with the help of a "faster lap ghost" and compare . Just to be sure.
After some updates , mainly the one that keep the gearbox out off the PP system , several of my older settings don't match anymore. Just need to reduce the PP with the help of ECU , power restrictor ... Tires... or else.