@JustEnoughDucks @EarMaster I'm not the original poster. I have seen lab test results supporting the LOWER water usage claim in ECO for common devices.
According to my own monitoring via smartplug, my own dishwasher uses about a 20 to 30% less electrical energy when in ECO mode as opposed to AUTO mode. It is a Bauknecht, which is likely very similar to your Bosch device in many ways (Bosch, Siemens, Bauknecht household devices all being manufactured by the same company...).