Citroen XM Forum

The wear on brake bands and clutches resulting from dropping into N when stopped must surely pale into insignificance compared to the number of times those same components have to operate, under far greater stress, in normal driving.

There's also the issue of the engine of an auto left in D with the brakes on having to work harder to maintain idle speed (the engine is under partial load). This inevitably results in increased emissions and fuel consumption, compared to a non-loaded engine. That, after all, is part of the thinking behind StopStart.

For very brief stops, staying in D is obviously sensible. For longer delays, flipping to N has got to be better. A really aware and alert driver - and I accept that doesn't cover everyone behind a wheel - will be keeping close watch on their rear view mirror when they have to come to a halt. If traffic is then approaching from the rear, it makes good sense to temporarily press the brake pedal (as an alert) - but not to keep standing on it long after the following car has come to a halt.

A lot of this is about being considerate of other road users, and doing some of their thinking for them.

Ciaran wrote: When you say 'An auto box switching into neutral wears because it is turning', do you mean that the box is still turning when in Neutral, even though there is supposedly no input from the engine in that circumstance, or did you mean the wear happens only during the short process of the shift from D to N and back?

Ciarán

When neutral is selected all the input side of the gearbox rotates due to the drive through the torque converter. The drive is disconnected further in the box.

If a car has STOP/Start function and the engine stops, then there is no input, otherwise there is still rotational input.

Well, I have no real experience with autos (I actually drove one once in the distant past, and fun it was, I had to reverse out with an oversized trailer from a double-decker car transporter of a train, I really can't remember how I did it) but, in my limited imagination, their biggest advantage is that you don't have to switch them all the time. Now if you force yourself to jump between N and D in rush hour traffic, wouldn't that take all the fun out of having an auto in the first place?

I have to admit I never had such strong sentiments about brake lights in front of me and with the clever but more complicated use of our parking brakes, I wonder if I'm not similarly guilty of using the normal brakes when stationary. I never gave much thought, it's so automatic (pun intended, of course).