I've worked with autonomous control for RC cars, and it's not that easy. The math is very fuzzy in highly dynamic an non-linear environments. That approach works in nice controlled environments, but will fail badly when assumptions about linearity and the effect of control decisions start to break down. Also with any open loop control model that takes dynamics into account, the state space is so large that planning at a high enough rate is a serious computational challenge. As vehicle speeds increase, the computation becomes a very hard problem.