Quote:
Originally Posted by Snatcher
Totally understand, but when doesn't the transmission stay in gear and slow down a lot quicker than when it's not in neutral? I've seen on my commute if I leave it in gear it slows down much quicker that it would in neutral. Wouldn't that help me get my car farther then have the tranny in gear to bring it back up to speed. Sometimes (obviously) when I go downhill I throw it in neutral (around 55mph) and it keeps speed real well than it would do in gear. Most of the time it actually gains a tiny bit of speed.
|
You may be able to go farther if you put your transmission into neutral while coasting, than if you leave it in gear, but consider this:
Every time you shift from neutral to drive, you're inducing a tiny bit of wear on the friction component of your transmission's geartrain. This is by design and is unavoidable. Also consider that automatic transmissions were designed to be shifted from neutral into gear while the vehicle is not moving, so as to minimize that wear I just mentioned. Shifting the automatic transmission in and out of neutral, while the vehicle is moving forward at a decent speed, is a sure way to shorten the life of the transmission, because you'd be inducing a lot of unnecessary wear in the geartrain friction component of the transmission.
Finally, there is a safety aspect that you might not be considering (or that you might be discounting). If you were to need to be able to accelerate out of a situation, it's far better to just have to step on the gas, than it would be to shift the car back into gear if it were in neutral, and then step on the gas.
By comparison, the lockup torque converter (at least in my truck) is designed to unlock and lock up while the vehicle is in motion, and while a significant amount of power is being fed from the engine into the transmission. My torque converter will alternately lock-up and unlock whenever I am stepping on the gas, then letting off of the gas pedal. However, that isn't going to wear out my lockup torque converter very much, and it's certainly safer than shifting to neutral and back.
Therefore, I recommend that your transmission be left in gear. The small amount of gasoline you'll save by switching in and out of neutral, above and beyond the pulse-n-glide technique I described, isn't worth shortening the life of your transmission, nor is it worth reducing your safety margin of error.