Your speed is almost certainly the biggest cause of your low MPG. Most people fail to respect how much work it takes to push against the wind. The power needed to push against the wind progresses exponentially with speed, so if you take the added power needed to go from 60 to 65 and add that much again, you won't make it to 70. It takes quite a bit more power (and gas) to make that difference between 70 and 75.
If you consciously keep your speed at 70 and never go to 75, you'll probably see a bigger difference in gas mileage than you expect. If you start going 65-70, you'll get another level of savings.
What's important to you? Minutes or gallons? You have to decide. Likely, you can't have both.
Better oil, better tires, care about tire inflation and even washing and waxing the car can help, but nothing is likely to affect mpg as much as your right foot.
If you consciously keep your speed at 70 and never go to 75, you'll probably see a bigger difference in gas mileage than you expect. If you start going 65-70, you'll get another level of savings.
What's important to you? Minutes or gallons? You have to decide. Likely, you can't have both.
Better oil, better tires, care about tire inflation and even washing and waxing the car can help, but nothing is likely to affect mpg as much as your right foot.