What real-world tweaks actually boost mpg in a modern midsize sedan?

[Addison_R]

I drive a 2016 Toyota Camry for my sales job, covering about 500 highway miles a week, and I'm trying to maximize my fuel economy tips to reduce costs, but I'm skeptical of many common suggestions; I already use cruise control, keep my tires properly inflated, and avoid aggressive acceleration, yet I'm still averaging only 33 MPG against the EPA's 39 highway estimate. I'm wondering if more nuanced techniques like hypermiling pulse-and-glide methods are worth the extra focus and potential safety trade-offs, or if factors like a slightly dirty air filter, old spark plugs, or even the brand of gasoline I use could be having a larger impact than I realize. For drivers who have successfully squeezed extra miles per gallon out of a modern midsize sedan, what were the most effective, real-world adjustments you made? Is using the air conditioning on the highway really less efficient than rolling down the windows, and have you found any measurable benefit from using premium fuel or fuel system cleaners in a car designed for regular?