Techniques are discussed herein for executing and evaluating simulations and/or emulations based on parameterized scenarios, such as driving scenarios used to analyze and evaluate the responses of autonomous vehicle controllers. A surrogate model may be determined by simulating points in a simulation parameter space with a simulator to determine the surrogate model while capturing the main features of the simulation model. Additionally, relevant areas of the parameter space, such as, areas containing parameters associated with events occurring infrequently during simulations, may be quickly identified using Bayesian optimization techniques. An iterative evaluation of an acquisition function may delineate a contour associated with the region of interest, and the surrogate model may be evaluated to determine a probability of returning a result corresponding to a parameter being within the contour. The probabilities may be further analyzed to determine scenario/vehicle performance metrics access the scenario parameter space.