I drive a lot for my sales job, covering about a thousand highway miles a week in a company-provided midsize sedan, and with fuel prices being so volatile, I'm trying to maximize my fuel economy to stay within my per-diem allowance. I already use cruise control and keep my tires properly inflated, but I'm wondering what other driving habits or minor vehicle adjustments actually make a measurable difference. For other high-mileage drivers, what techniques have you found most effective for squeezing extra miles per gallon? Does using premium fuel in a car that only recommends regular provide any benefit, and how much does using the air conditioning versus rolling down the windows at highway speeds really impact efficiency?
Two quick wins: plan routes to minimize left turns and stop-start, and anticipate traffic so you’re not braking hard or accelerating hard. On highway miles, keep a steady speed with cruise control when it’s safe, and aim for smooth, gradual throttle. A couple of weeks of tracking your drives will show the biggest gains.
Premium fuel: if your car’s owner manual says regular, there’s usually no MPG benefit to using premium. The only time it helps is if you hear knocking under load or see a recommended octane higher than regular. If you want to test it, run a tank with premium and compare your miles per gallon to a tank with regular, but don’t expect dramatic gains.
On the AC vs windows question: at highway speeds, opening a window costs more due to drag, and AC costs energy too. In practice, closing the windows and using the AC (preferably in recirculate mode when it’s hot) is often more efficient than cruising with windows down. The exact difference varies by car, but plan for a few percent impact depending on speed and outside temperature.
Other habits that help: keep tires at the recommended pressure, remove unnecessary weight, and avoid roof racks unless needed. Regular maintenance matters too—air filter, spark plugs, and alignment can shave a few percent off consumption. Use a steady, long-horizon approach rather than chasing tiny tweaks; small changes compound over hundreds of miles.
Quick 4-week plan: baseline your MPG on a typical weekly route, then try one change at a time (e.g., speed steady at 60–65 mph, then try a route with less stop-and-go). Log fuel and miles, note weather and traffic, and compare week-to-week. If you want, I can help you build a simple MPG log template.