Is there any hope?..

[BlackSE-R]

I think I'm beginning to lose my head. I have tried everything people have
suggested to me. I checked the famous archives. I talked to mechanics. I
keep on getting low miles per gallon. Last time I tanked: 137 miles; 8.402
gallons. That's roughly about 16.3mpg. I drive a 92 se-r, no mods, 115k
miles on it, I bought it from this one guy who had to sell it, because he
was forced to leave the country. Other se-rs get more than 20mpg. Guys, if
this happens to me, I'm popping the Champaign bottles and having a huge
party. Any suggestions on how I can fix this problem? I'm hopeless now...
Thank you up front, for any suggestions...