Ancient wrote:I only leave the car in gear on slopes. No disadvantage I am aware of in leaving it in gear when on the flat, just I try to make every driving decision with deliberation ('is this safe/legal/necessary?') rather than automatically. Of course, most of the actions involved in physically driving are now 'automatic' and our minds will build up a network of familiarity with situations which actually helps us drive safely (experienced drivers have built up a 'picture' of how many types of junction and other interactions with other road users work); but the decision points: Go/no-go, this surface therefore this speed, how do I park here, I deliberately try to make on a conscious level as an unconscious decision is too easily 'fooled' by endogenous factors.
I'm going to take issue with this, if I may.
Whilst I agree that there are many things that drivers often do automatically that, IMO, should be deliberate, such as indicating and changing gear. There are also things that can and should be done automatically if doing them every time is of benefit. At least it then frees up a bit of brain power to concentrate on other things. For example, I don't have to "consider" using a seatbelt every time I get in the car.
Putting a car in gear, automatically, when it may not be absolutely necessary, is completely harmless. Not putting it in gear, when there could be a real chance of the handbrake failing could result in disater.
I had a Citroen BX many years ago where the handbrake would fail when the disks cooled down (it was a brand new car). I found out about it when one of the neighbours asked why my car was in the middle of the road - it could have been much worse. From that moment on, I have NEVER left a car parked out of gear.