Question Why are multi-speed axles and auxiliary transmissions used? Answers To make a vehicle operate more smoothly To provide extra gears To improve a vehicle's gas mileage Explanation On many vehicles, multi-speed rear axles and auxiliary transmissions are used to provide extra gears. Take a FREE Practice Test Now This questions appears in the following tests: Louisiana Knowledge Test Class A , Ohio Knowledge Test Class A , Rhode Island Knowledge Test Class A , Nebraska Knowledge Test Class B , North Carolina Knowledge Test Class B , Idaho Bus ,