1998 Lincoln Continental Owner's Manual - Page 102
1998 Lincoln Continental Manual
Page 102 highlights
Driving D (Overdrive) The overdrive position is the normal driving position for an automatic overdrive transaxle. It works the same way as 3 (Third) but shifts to a fourth gear - an overdrive gear - when your vehicle cruises at a constant speed for any length of time. This fourth gear will increase your fuel economy when you travel at cruising speeds. Overdrive may not be appropriate for certain terrains. If the transaxle shifts back and forth between third and fourth gears while you are driving hilly roads or if your vehicle requires additional power for climbing hills, shift into 3 (Third). When to use 3 (Third) 3 (Third) eliminates the needless shifting back and forth between third and fourth gears that your vehicle may do when driving on hilly terrain. It also gives more engine braking than overdrive to slow your vehicle on downgrades. 102