A system comprises a controller for a vehicle. The controller comprises a processor and a memory. The memory stores instructions executable by the processor. The controller is programmed to receive data values from a sensor to detect infrared light. The sensor is in a line of sight to a vehicle foot well. The controller is further programmed to activate a knee bolster upon determining, based at least in part on the data values, that an object is present in the foot well. The controller is yet further programmed to deactivate the knee bolster upon determining, based at least in part on the data values, that there is no object in the foot well.