I normally drive 70 MPH & get 17.3 mpg. I bumped up the speed to 75 & the milage dropped 1.2 MPG. Does this sound right?

 

Sounds about right. I know that when I travel on the freeway, I try to maintain 68-70MPH for optimal fuel economy. If I run 'er up much higher, it drops like a brick. It's like an exponential decrease in MPG with increased MPH beyond a certain point

 

Once you hit 2000 RPM the mileage goes way down

 

70mph is like 1950 RPM and 75 is like 2100 RPM. 2000 RPM is like a big cliff for mpg

 

I drive 75 because I don't hear the turbo enough at 70

Maybe it would be cheaper to mod the intake or exahust for louder turbo

On topic, I have noticed the same thing... above 2k rpm and mpg drops like a brick. On the plus side, I'd have to cruise at about 85 to get what I got before the TSB at 70.

-Sam