What is a key indicator of a vehicle's braking performance?

Stopping distance serves as a key indicator of a vehicle's braking performance because it directly reflects how effectively a vehicle can come to a halt when the brakes are applied. A shorter stopping distance indicates that the brakes are functioning well, allowing the vehicle to decelerate quickly and safely. This can be influenced by various factors, including brake system condition, tire grip, road surface, and vehicle weight.

In contrast, other options such as fuel efficiency, engine temperature, and wheel alignment, while important aspects of vehicle maintenance and performance, do not provide a direct measure of braking effectiveness. Fuel efficiency pertains to how well a vehicle uses fuel, engine temperature relates to the performance and health of the engine, and wheel alignment affects handling and tire wear rather than how quickly the vehicle can stop. Hence, stopping distance is the most relevant indicator in assessing the braking performance of a vehicle.