My landlords replaced a malfunctioning old one (probably at least 20 years old, from what I could gather Googling the serial number) with a new one, and even though I suspect the new one is a “cheaper” model relative to the old one in the hierarchy, and does take longer to do a load, part of that is because I select the water-saving mode, and part of it is because it heats the water up to a higher temp than the hot water as it come in from the heater.
My electric bill did not change, and the new one is “better” in that it has a lot more choices of ways to run it, as well as ways to put in the dishes. It also has separate sprayers for the top and the bottom.
It’s like when, just a few years ago, I stopped driving a mid-line car that was 20 years old for a no-frills efficiency car that was brand new. The new car wasn’t as powerful in that it couldn’t go from 0 to 60 in a blink (although, I still beat out SUVs and older luxury cars from lights), and doesn’t have power windows, but it has a ton of things the old one didn’t have that are considered safety features, and kind of feel like luxury items to me, but come standard now, like a back-up camera, and a rear window defogger.
I could probably run my new dishwasher on settings that would make it do a load faster, but then it might show up on the electricity bill. It has a power-saver button, and I don’t know what it actually does (maintenance did not give me the owner’s manual, and I have not felt like Googling for one), and it’s set to on, which I assume makes it take longer, because the water pressure may be lower, and the spray arms may have less resistence, but the dishes look clean when it is done.
It also has a “rinse hold” option, and a “no heater” option, which means that if I don’t have a full load, but I want to rinse them in hot tap water, I can do that, and leave them for next day’s wash. Old one had no such options. That is probably a bit of an energy saver, and save detergent.
I splurge and buy those “pacs,” because for a long time, it was the boychik’s job to run the dishwasher, and when he was 8, we didn’t burden him with measuring soap. He just turned 16, and he is learning the settings on the new washer, but one thing at a time.