Ok I found the structedit mod which is a fantastic idea. It lets you change about half of the handling settings, while the other settings are either missing from the list or they won't let you change them. In particular are the suspension damping settings that won't change which are extremely important when tuning for high speed/acceleration handling maneuverability.
Also the handbrake is missing. I've found with enough tinkering and mastering to be able to get vehicles to handle extremely awesome, very fast, and using handbrake around corners with success. But it requires the use of all the settings. They all work in sync together.