I tried searching the forums for anything pertaining to this, but couldn't find anything.

I was wondering how accurate the ECU readings are on the Accessport. I did a highway trip and it showed I was getting an average of 24 MPG. To me, these readings seem to be far off; for reference I have an '07 GT M/T

I know the RX-8 isn't an economy car, but I'm trying to get an idea of what my mileage is based on driving habits, as well as any possible improvements after tuning.

So has anyone compared the readings for fuel economy on a full tank with the Accessport vs. manual calculation?

 

Why don't you calculate your mileage yourself manually and find out? Who uses a Cobb to calculate gas mileage anyway.........

 

I'm interested to see what its getting in real-time, I have been calculating gas mileage manually, and what I'm saying is what the Accessport is showing when i'm on the highway, and what I'm inferring from the manual calculations seem to be way off.

Which also makes me wonder how accurate any of the ECU readings are.

 

calculating MPG via obd2 isn't accurate. It is a function of Vss, MAF, and AFR. Being as the car is running in open loop at highway speeds, the numbers aren't exactly all that accurate. I too see numbers like 25 - 26mpg from my 'device' ..... am i really getting that... no.

 

Thanks for the explanation, that's kind of what I figured.