Question When leaving a vehicle unattended, a driver should: Answers Always set the parking brake. Only set the parking brake if the vehicle is parked on a slope. Deflate the tires by 10 percent. Explanation Always apply the parking brake when leaving your vehicle unattended. Take a FREE Practice Test Now This questions appears in the following tests: Hawaii Knowledge Test Class A , Connecticut Knowledge Test Class B , New Mexico Double , Louisiana Air Brakes , Michigan Air Brakes ,