I don't use the Eco programmes on the dishwasher or the washing machine. The dishwasher doesn't wash at the temperature it says on the eco setting and everything comes out with water droplet marks on, not properly dried and often not properly clean, so it's no economy because you have to wash things twice.
The German "Test" - the equivalent of "Which" measured the temperature of the water in a 60° eco programme - it was 27°!!! This shocked me and I haven't used the eco programme since. I often set it to a higher temperature than the one I want as the water is never heated to that temperature.
The default setting in the dishwasher is the eco programme and DH just presses the button if he switches it on, so it runs on that, and then I have to put half the dishes back in again because they come out not properly washed.
It's more important to make sure the filter is regularly cleaned out and the spray arms are not bunged up.