I was able to get what amounts to over 500 miles on a tank when I bought the car. I adjusted the valves, and my mileage dropped, and probably took a few thousand miles to get back to where it was when the valves were too tight.

I am getting 33 MPG on the highway now if I keep my speed between 55-65. Around town, which means taking a 1 mile trip here and there, I can be as low as 24 MPG. Generally, I get 400 per tank around town and well over 500 on the road.

Of course good valve adjustment affects the mileage, but I am inclined to believe that an engine that has not lost any compression will be more important when it comes to good mileage.