Like Masis said, very nice update overall. I love the idea with the classes, I mentioned it a while back and I'm happy to see it finally arrive.
I'm not sure exactly what parameters are read from the handling.meta for each class, but few odd vehicles (even with the same values) can very much behave differently.
Some vehicles like the Mazda RX-7, Drafter 8F and Subaru Impreza to nearly flip when taking sharp corners.
This is mainly caused by the "vecCentreOfMassOffset" and on some occasions the "fSuspensionUpperLimit" and "fSuspensionLowerLimit".
Some vehicles I believe have certain flags enabled like the Mazda RX-7 which uses the realistic ABS flag (00000040) which affects the braking by a big margin. From a racing standpoint these cars would be at a big disadvantage. Same vehicle would also need the tire clipping flag, wheels pop through the bodywork.
Some vehicles like the r35, the backend steps out too much, this is mainly caused by the "fTractionBiasFront" parameter being set too high. On some cars, when cornering at fast speeds "fTractionCurveMax" and "fTractionCurveMin" need to be adjusted to stop the vehicle from spinning out at high speeds.
Other than that, I'm really happy with the update. It's gonna be great especially for the racing scene and police chases, thankyou