The current precision is not 100% perfect but very very high. Nothing to even slightly worry about and with the wheel using the helper position it is completely unnoticeable. Even when you zoom in all the way. To answer your question, the FBX export format does not nearly support all this nifty stuff my brother used in 3ds max. Even if it would, you would not gain much or anything.This is because of the math involved. Whenever you do IK or invert a function in a non analytical (non closed-form) way like i did in the engine or max does for IK, you only have an approximation. This is true in 3ds max as well. Even "look at" is not 100% perfect all the time and more complex inverse stuff only gets worse. This is a fundamental issue. This part of mathematics is called "numerical analysis" and it is used for nearly everything in the engine that is not straight forward. Even relatively simple stuff like the inverse of a 4th order polynomial does not have a closed-form and thereby perfect solution (This is unrelated to numerical calculus precision which is yet another problem).
Looks great. I like the water drops on the lens when the vehicle goes through the wet. Are you planning on doing a first person option?