Two things I have done over the years to save gas & wear and tear have me wondering if they help or hurt my car.
First thing…when I come to a stop light I shift my automatic transmission into neutral to save wear & tear on the engine, does it hurt doing that & does it save fuel. Secondly when I accelerate I turn off the A/C until I hit cruising speed to save gas and lessen the load on the engine. Again does this hurt or help?
You are going to get some very different opinions on your first notion, that of shifting into neutral.
There ought to be general agreement that you do not save any wear on your engine and that there are no measurable fuel savings. Wear & tear on your transmission, however, is another matter.
The prevailing opinion is that a bit of wear takes place each time you do the shift. You can avoid such wear by leaving your car in gear for the duration of thetrip. My own opinion is that such presumed wear is negligible. If it is your ingrained habit to make the shifts you may continue to do so without guilt. But we all agree that your method definitely does NOT save your car or fuel in any way!
There ought to be little disagreement on your second quirk, that of shutting down the A/C when you plan to accelerate. Useless! What a wasted effort! Here’s what happens: Your computer automatically releases the A/C compressor when it senses acceleration! So take my advice and leave that A/C switch alone; let the car do it for you.
Shifting an automatic transmission into neutral at stops has been discussed endlessly on this board and the old version. I think the general consensus is that it doesn’t help, and may cause negligible wear to the transmission.
As for turning off the A/C, the car does that automatically, at least newer ones do, when giving strong throttle application. Again, I don’t know that it helps at all turning it off manually, but I don’t think it hurts either. Only thing I would caution against doing this is the distraction it causes. One of my sisters got into a bad car wreck because she was turning the A/C on and got distracted, ended up going straight into a ditch at about 70 km/h. Granted, she never was a very good driver, but still, it is a risk.
Don’t bother with either. They will not help or hurt enough to worry about.
Leave it in D.
Saves wear and tear on the tranny internals AND on the gear select mechanism.
The shift select mechanism does have bearings and will wear out.
Here’s what happens: Your computer automatically releases the A/C compressor when it senses acceleration! So take my advice and leave that A/C switch alone; let the car do it for you.
Maybe, maybe not; it depends on the car. However, I wouldn’t bother shutting it off because you are going to end up saving a very small amount. Why not just accelerate slightly more slowly if you want a little more economy?
My opinion is that any potential fuel saving is in the less than miniscule category with both scenarios.
I place shifting the auto trans in neutral and turning the A/C compressor on and off into the same category also. Every time you shift the transmission back into gear or turn the air compressor on you’re slamming the clutches in the transmission together and you’re slamming the compressor clutch hard also.
Why contribute any more to the beating they already take.