Quarch (they make awesome power analysis/power injection equipment) did an investigation in to their office dishwasher's "Eco mode" a couple years ago. It was interesting: https://quarch.com/news/my-dishwashers-eco-mode-did-not-save...

The quick conclusion? "Quick Wash" uses less energy and water than "Eco Wash". "Intensive Wash" uses more energy than both.