* Going uphill: Overdrive might cause the engine to struggle and downshifting is necessary for better performance and engine protection.
* Accelerating quickly: Overdrive is for fuel efficiency at cruising speeds; it's not designed for rapid acceleration.
* Driving at low speeds: Overdrive is less efficient at low speeds.
In most normal driving situations on flat terrain and at highway speeds, using overdrive in a 2005 Jeep Wrangler will improve fuel economy.
