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.

Maybe Skip the Acetone

Yesterday's post talks about the possibilities of adding acetone to your gas to get better gas mileage. Here is a second opinion. According to Bobby Likis in this video, acetone might clean carbon deposits out of your fuel system, improving the gas mileage a little. However, cars are not designed to use it. Acetone might damage the wiring of the fuel pump or the fuel injector system. Also all of the rubber seals in your car could be damaged. Bobby's recommendation: don't put acetone in your car. Watch and see for yourself!