MPG issues for a 2000S

[dkh]

Please forgive me if this question has already been hashed over many times before. I did a search and couldn't find anything - maybe I didn't use the search correctly, but what kind of real world MPG figures should I normally expect to get in a 2000 S? I know, I know, quit mashing my foot down all the time and it will improve but still I haven't had better than 19 MPG in a tank yet - this is driving mostly highway miles, probably about an 80 percent highway, 20 percent city combination.

I've heard that some people get better mileage after replacing or cleaning their MAF sensor but that's when they get a CEL that indicates a failed MAF. Is it possible to have a component like the MAF or oxygen sensors cause lower gas mileage without causing the check engine light to come on? I've wondered if it would be worth the risk of possible damage to clean the MAF to see if it improves MPG. Or maybe replace the OS? Is there a diagnostic tool I could plug in to the computer that would show any possible issues that could cause lower MPG?

I don't expect this car to be able to get Honda Civic mpg but it seems like it would be able to get closer to 25 or 26 mpg sometimes. Years ago in my 911T I didn't worry too much about mileage because I didn't drive it that much and fuel was cheaper but this car is my daily driver and a few mpg improvement would make a big difference.

Thanks for sharing any knowledge you have about this.