Abstract: Techniques for generating simulations to evaluate an update to a controller. The controller may be configured to control one or more functionalities of an autonomous and/or a semi-autonomous vehicle. A simulation computing system may receive a request to evaluate a first controller. The simulation computing system may generate a simulation based on data associated with a previous operation of the vehicle in an environment, the previous operation being controlled by a second controller (e.g., standard for evaluation, control version, etc.). The simulation computing device may cause the first controller to control a simulated vehicle in the simulation and may determine whether to validate the update to the controller based on a difference between first metrics associated with a control of the simulated vehicle by the first controller and second metrics associated with a control of the vehicle by the second controller.