Overdrive or OD is the highest gear in the transmission in an automatic car . It brings the RPM of the engine down at a given road speed to facilitate better speed and fuel efficiency. It also helps your car to provide the best performance in higher speed cruising. Overdrive helps when you drive at more than 50mph.When should I use Overdrive?
In general, overdrive technology is suitable only for cruising . That is the only situation when you could make good use for it. Do not under any circumstances mistake overdrive with high-performance or you could get in big trouble. Cruising saves fuel and when done with overdrive cruising can really save you some money. Aug 1 2019What is the gear ratio for overdrive?
The overdrive gear unit is an independent planetary gear unit with a gear ratio less than 1.0 (approx. 0.7-0.8). It is combined with a conventional 3-speed planetary gear unit and is equivalent to the 4th speed gear. The overdrive gear unit consists of the planetary gear set, brake (B0), clutch (C0), and one-way clutch (F0).