[Tempest1981]

You say it's useless, but then say "maybe you will save a few bucks on gas if you follow the indicator". Isn't that the point? To teach/remind you how to save gas?

I agree that it is imperfect, and imo annoying/distracting. But it may work for a large number of drivers, most of the time.

[fazzone]

My point is that they far over-prioritized fuel economy. If you actually drive like that you will be spending a lot more time changing gears than necessary, and that almost any acceleration will require a downshift. I wouldn't recommend trying to stretch the gas mileage in the snow, for example, since you might need power to recover if you start to slide.

[blub]

Completely agree. Those indicators ignore that we can't accelerate as fast as a double-clutch automatic in case of emergency.

[rini17]

Overusing clutch is not such a big problem, but that it leads the driver to keep low rpm. Especially diesel engine is sensitive to that and can be damaged.

[vetinari]

It is a trade off - you can trade a some of engine lifetime for a slightly better consumption by keeping the engine in low rpms, where it is stressed more than it should. That's exactly what the indicator suggests.