shift gear to N at red lights increase fuel economy??

[Blue Mountain Raider]

a friend told me that by shifting to N at red lights it'd increase the fuel economy a little bit, because the car would no long want to go forward. is that true? i guess it will increase gear wear. thanks

[Dblock2151]

I hear it's actually better for your transmission. When I went to India, all the driver's would switch to Neutral whenever they could, if their car was Auto.

[SilverBullet]

Interesting. So it is good for the transmission to shift to N while idling at a light or in traffic?

[JCL]

DriverX5: Assume you mean with an automatic. If it is with a manual, definitely move it to neutral to save the clutch throw-out bearing.

I can't imagine that there would be any measurable fuel saving by moving an automatic into neutral at a traffic light. If you cared about fuel economy that much, you would turn your engine off if you were going to idle for more than about 20 seconds. No, I am not advising you do that, since you wouldn't be able to move if you saw someone bearing down on you, but it is the principle exploited by hybrids.

When you are stopped at a traffic light in drive the gears in an automatic aren't moving, so there is no gear wear. The gears are attached to the output shaft. The disconnect is at the torque converter, after the engine and before the transmission. What you are doing is generating a small amount of heat due to the slippage in the torque converter. That heat is dissipated by the transmission oil cooler.

With heavy equipment, powershift transmission life can be correlated to the number of lifetime shifts, more than the number of hours of operation. I don't have similar studies on automobiles, but there are reasons to believe that there would be similar correlations. It is only when you shift that the automatic transmission clutch packs and bands wear as they engage. I would trade the wear and tear on the trans fluid for the wear and tear on the clutch packs any day.

Jeff

[asawadude]

Sure - it makes plenty of sense. Think about it - at a stop light, you have the the auto tranny engaged in drive and your foot is on the pedal. Obviously there is a small load on the entire drivetrain that would be eliminated by putting the transmission into neutral. RPM's will drop slightly. I have no idea what savings is realized at the fuel pump; it probably varies by driver and type of driving. Not worth doing in my book. If I'm going to shift, I'll get a car with a manual transmission.

[Thunder22]

This is an extremely bad idea.

If you need to accellerate away from a threatening situation such as someone about to hit you, you're at a horrible disadvantage.

Also, it is illegal in some states to do this.

also:

Myth No. 5: It's best to shift an automatic transmission into Neutral at red lights. This myth stems from the idea that keeping the transmission in Drive while stepping on the brake wastes fuel and causes unnecessary wear on the driveline. In fact, actual engine wear and fuel loss are minimal.

Regularly shifting from Neutral and back into Drive when the light turns green, then immediately stepping on the gas, can wear — albeit slightly — on the transmission, driveline and engine mounts. Ultimately, these stoplight antics probably won't amount to any measurable harm or good; they're likely just a habit by folks who need to keep their hand busy with the gear selector. Our advice? Get a stick shift.

[Quicksilver]

No. Not true. It's a waste of time and it's dangerous.

Originally Posted by Blue Mountain Raider

a friend told me that by shifting to N at red lights it'd increase the fuel economy a little bit, because the car would no long want to go forward. is that true? i guess it will increase gear wear. thanks

[Dr_Smith]

a bit silly also. I mean, if you're driving around a bimmer why are you worried about saving a minuscule amount of gas?

[AzNMpower32]

I asked before. The resounding answer was a NO.

http://www.bimmerfest.com/forums/sho...d.php?t=165110