A higher gear ratio will cause (final drive)?

A higher gear ratio in the final drive of a vehicle typically results in lower engine RPMs during cruising speed. This happens because the axle turns more times relative to the engine, allowing the vehicle to cover more distance with each engine revolution. As a result, the engine doesn't need to work as hard at maintaining speed, which can lead to improved fuel economy.

By operating at lower RPMs, the engine can often run more efficiently, consuming less fuel while maintaining the desired speed. The combination of these factors indicates that a higher gear ratio will indeed enhance fuel economy while still allowing the vehicle to operate effectively at cruising speeds. Hence, both lower RPM at cruising speed and high fuel economy are benefits associated with a higher gear ratio.