I have a 5spd kia. Drive in your car should already be Overdrive. I could be wrong, but that's usually how most cars are made. Overdrive basically shifts into it when you are just crusing so you are not cruising at such high RPMS. Saves gas. My fifth gear is overdrive in my car, so when Im going over 35 or 40, Ill pop it into 5th and just cruise at 1 1/2 or 2 grand.