I have an 04 rx8 and im getting 9.19mpg. I beat the car a little but still seems to just drink gas. My gf got better mileage in her Hummer

 

I don't mean to be a jerk, but the very first sticky in this subfourm has the answer to your question. The very first one. This forum has a bit of a reputation for being hard on new members. The reason for that, from my estimation, is that new members almost never bother to search for solutions and instead expect to be spoon-fed, simply because they exist and have this car. We get very tired of answering the same questions over and over and over and over and over and over... That's why we create stickies, that new members never bother to read. Sigh.

https://www.rx8club.com/new-member-f...causes-249529/

• highway gas mileage less than 17mpg
  • Ignition failure
  • e-shaft sensor fouled
  • engine compression loss
  • vacuum leak
  • front O2 sensor failure
  • MAF fouled
  • dragging brakes
  • old transmission oil
  • old diff oil
  • failing diff
  • carbon choked engine
  .
  
  

 

How old is the catalytic converter? Have you replaced any ignition components in the last two years?

 

I apologize for being new to this whole forum thing in general. I bought the car a few months back and the guy told me he gutted the cat

 

Lucky he gutted the cat or you'd burn up your floor, and engine.

Ignition coils are only good enough to get car out of dealer (just my opinion), so go get some new ones if you're light on funds, or splurge and get the BHR kit with Chevy Yukon coils.

I put my BHR ign kit on at 22k miles, and it instantly perked up.

I was getting 5mpg on the track at full blast and full brake, and after the kit, I got at least 10 mpg like that.

 

Welcome, and a suggestion...

Look at the congrats thread in my sig. Do all the things that have the word "clean" in them. Then reset the ECU (20 brake stomp) and do a warm up cycle (start it cold, let it idle until fans come on).

Then start replacing stuff. I too would do coils first. IMHO, the yukon mod is worth it, but expensive. a set of autozone coils are a fraction of the price and a better choice for troubleshooting