Collision avoidance is a crucial function for all ground vehicles, and using integrated chassis systems to support the driver presents a growing opportunity in active safety. Here we consider the scenario of an impending frontal collision with a stationary or slower moving vehicle in the same driving lane. Traditionally, researchers have approached the required collision avoidance manoeuvre as a hierarchical scheme, which separates the decision making, path planning and path tracking. This paper approaches the collision avoidance directly from the perspective of constrained dynamic optimization, using a single optimization procedure to cover all three aspects within a single online optimization scheme. The key innovation is in selecting an appropriate cost function and applying Model Predictive Control (MPC). A risk-sensitive weighting parameter alters the decision bias between straight-line braking and steering to avoid collision.