By choosing the appropriate cycle on your dishwasher, you can save considerable amounts of water and energy. You may be surprised but in most cases, short-cycle programmes do not help you to save energy.
An “economy” or “energy saving” cycle is usually the one that you should use, even if it lasts longer than others.

The most energy used by a dishwasher is to heat up the water, hence, when the load is not unusually dirty, you can choose 50°C or lower temperature programmes and still achieve great results.