My car has an 'econometer'', and I am not gonna lie, it does influence my driving habits as I drive to keep it in the green, so no blasting away from traffic lights, progressive acceleration and I cruise in the 100-120 km/h range. 110 km/h in 6th gear seems to be the perfect spot for it.
I do it appropriately, though. If I need to get in and out of traffic I don't muck about and will step on it, ensuring I keep up with the flow on traffic and don't inconvenience other road users.