OK, well, I have to give you credit for admitting that the most current info or experience you are basing your opinion on is at least 15 years out of date. Hopefully you can also recognize that such out of date info is a poor basis for forming an opinion.You are right, I have never owned one or driven long term. However, at one point in my life I was a test driver for Mercedes and we did had to test that start stop system, different cars, different engines and transmissions, but always the same procedure. 8hr shift, 6.5hr driving time. That was back in 2007 I want to say, and starting back then I did tell myself not ever to buy a car with that feature.
Sure, they might have gotten better over time, but just imagine, it's like all the firetrucks in an emergency. They start the engine and go. So these cars roll up to the light, shut off and once it's green start up and you accelerate. Oil pressure, everything is down. While I idle my car, everything turns and is lubricated. Once green I accelerate an already moving engine.
My opinion is that it's easier on the material and the fuel savings are neglectable.
And don't get me wrong, it's great that technology keeps evolving, if we like it or not. What bothers me is that you cannot omit to it anymore when buying a car. It's not an option, it's standard and you'll pay for it, if you want it or not.
Have you ever heard of Moore's Law? It is well-known theory regarding the evolving capabilities of computer systems over time. Do a little research on that topic and you'll see how it applies to this subject.
Anyways, like I said, the 2021 Malibu I drove for 9 months got 15%-30% better mileage than what you quoted for your smaller 2010 Ford Fusion, and I don't think the difference was as simple as a Ford vs Chevy issue.
But as always and with so many things, YMMV (pun intended).
