Should the over drive in a car be on all time?

It is not recommended to keep the overdrive on all the time. Overdrive is a feature in vehicles that allows the engine to run at a lower RPM at higher speeds, improving fuel efficiency. However, keeping it on all the time can put unnecessary strain on the transmission and engine. It is generally advisable to use the overdrive button when driving at a steady speed on the highway, and disengage it when encountering hills, heavy traffic, or sudden changes in speed, as it can cause the transmission to shift in and out frequently, leading to increased wear and reduced performance.