What is Overdrive in a Car?
Although overdrive sounds like a term related to a vehicle’s high-performance attributes, it is the opposite. This feature – generally turned on and off with the touch of a button – reduces an engine’s revolutions per minute (RPMs) at sustained higher speeds, thereby lessening a vehicle’s fuel consumption and making it more efficient in highway driving. By limiting the amount of strain on the engine, overdrive also results in quieter and smoother operation with less overall engine wear. If employed correctly and consistently, it can reduce engine maintenance issues over time and extend the life of a vehicle’s powertrain.
Overdrive’s functionality is to serve as a high gear mode for a vehicle and can be looked at as an added gear that widens the transmission’s shifting range at its top end. By shifting higher, the powertrain reaches lower gear ratios (the higher the gear, the lower the ratio) and allows the engine to perform at lower RPMs during highway cruising of 50 miles per hour or more.
Whereas a vehicle will normally operate at lower gears with greater output and torque, overdrive inhibits acceleration and maximum power. The vehicle is considered over-geared or overdriven, making it so that top speed and performance are sacrificed for greater fuel economy and a more effortless driving experience.
In many current vehicle models, overdrive is a less prevalent feature due to modern transmissions that offer higher gearing (fifth and above) intended for efficient cruising. If you compare cars, you’ll discover the automatic transmissions in new vehicles typically don’t require a driver to manually activate the feature.