Optimal MT shift points.

[minnyar]

Originally Posted by goliath1812

If you downshift all the time, instead of putting it in neutral and coasting, you'll get better mileage by using DFCO.

Debatable. It really depends on how far away that red light/stop sign/etc is. There is a point at which coasting is going to be more efficient than downshifting. Downshifting is practical if I need to come to a stop, or want to casually reduce speed without using the brakes, but if a light has turned green and I know that by the time I get to the light 1/4 or 1/2 mile away all the cars in front of me are up to speed it makes more sense to coast. Think of it this way: Lets assume the speed limit is 55. Am I really saving fuel by leaving the car in gear or downshifting to obtain DFCO and I lose 20 mph of speed (at which point traffic ahead is moving sufficiently to speed up) only to have to accelerate the 20 mph back to 55. If the car was in neutral I may only lose 5 mph over the same distance. Although the engine was burning fuel by idling rather than DFCO, I only need to accelerate 5 mph. You are never going to use more fuel, in any car, than during acceleration. So while your point if valid, if you need to stop or decelerate quicker, it really depends on the distance involved.

[BailOut]

Originally Posted by minnyar

Debatable. It really depends on how far away that red light/stop sign/etc is. There is a point at which coasting is going to be more efficient than downshifting. Downshifting is practical if I need to come to a stop, or want to casually reduce speed without using the brakes, but if a light has turned green and I know that by the time I get to the light 1/4 or 1/2 mile away all the cars in front of me are up to speed it makes more sense to coast. Think of it this way: Lets assume the speed limit is 55. Am I really saving fuel by leaving the car in gear or downshifting to obtain DFCO and I lose 20 mph of speed (at which point traffic ahead is moving sufficiently to speed up) only to have to accelerate the 20 mph back to 55. If the car was in neutral I may only lose 5 mph over the same distance. Although the engine was burning fuel by idling rather than DFCO, I only need to accelerate 5 mph. You are never going to use more fuel, in any car, than during acceleration. So while your point if valid, if you need to stop or decelerate quicker, it really depends on the distance involved.

Well said, minnyar.