Does Coasting in Neutral Save Gas?

If you are going to slow down for a turn or a stoplight ahead, should you put your transmission in neutral and coast along to a lower speed? Bobby Likis explains that with an automatic transmission, this will use more gas than leaving the car in gear. The reason is because while you are coasting in neutral, the engine is running in idle and receiving fuel to power it. However, if you are coasting in gear, the engine management computer detects that no power is needed and cuts off all fuel to the engine. Engine revolutions are maintained by drawing energy from the rotating wheels and drivetrain ... it is something like the way electric engines can recover energy while braking. Cutting off fuel flow means you will use less gas then letting the engine idle in neutral.

So to save on gas with an automatic transmission, leave the car in gear as you coast to lower speeds.