What type of transmission provides increased fuel economy?

Overdrive manual transmissions are designed to provide increased fuel economy by allowing the engine to operate at a lower RPM while maintaining a given speed, especially on highways or at cruising speeds. This is achieved through higher gear ratios that reduce the engine's workload and, consequently, fuel consumption. Because the engine doesn't need to work as hard at higher speeds, the efficiency improves, leading to better fuel economy.

This type of transmission is equipped with an additional gear that is over the direct drive ratio, which typically engages at highway speeds. When engaged, it minimizes engine revolutions per minute (RPM) while still delivering the necessary power to the wheels, making it particularly advantageous for long-distance driving.

In comparison, standard manual and automatic transmissions may not have the same degree of efficiency at higher speeds, as they might rely more heavily on lower gears that increase engine RPM. Though CVTs also provide good fuel economy by allowing a more efficient power band, the context of the question suggests a focus on traditional gear setups, which makes overdrive manual transmissions an ideal option.