Aerodynamics might be at play more than the efficacy of the motor at those speeds. Although not sure what vehicle gets great milage at 90-100MPH
most vehicles MPG drops after 55.
I track my MPG with fuelly just so i can have a quantifiable idea of how my engine is running, would be interesting if more people were to join and track their fuel ups.
I'm really disappointed with the efficiency of the GM motor in the Sling. Drove to Laredo (about 300 miles) and reset the calculator. I avg about 18 mpg when driving at the speed I'd like to 90-100mph in 5th. But it freaking struggles to cruise at that speed...
Had to drop to 75-80mph to get to 20-21mpg...
I don't care in the city when I'm launching and driving hard, but highway cruising? Come on man!!!
I have not had and problems running at those speeds, I had the cruise set at 100 MPH coming home on I-26 from SSITS for the last two years. Even NA with Bob's tune I have still been averaging 29 MPG average for the whole trip, including the fast mountain driving. I only check mileage anymore when I go on a trip and I get the average for the whole trip, most times it is an average of about 1,700 miles at least.
I was getting 34 MPG before Bob,s tune. It runs a little rich now, with the tune.
^^^^
Lazy? 
The daily driver and SUV have done this to me...
But... I did start that @Rob the Slob. Reset a trip calculator and will do on next fill up.
Wait, what?
What could be wrong with my gas mileage? I set the cruise control on and to stay at 90mph in 5th gear, the revs are at 3.5... Is that right? Maybe my computer is just off? It typically will take 6.5 to 7 gallons when I fill up, after it states 60 miles left in the range.
It drops quick in that territory and then the flashing low fuel will kick on...
When the light comes on you only have 1 gallon of gas left. As far as using the computer for the mileage, my experince it was always 2 to 3 MPG lower. I do not pay any attention to the RPM's anymore. I just know you can run all the way up to 120 mph in 4 gear. As far as running the motor hard the power band is from around 3,300 rpm to about 5,600 rpm
I was getting 34 MPG before Bob,s tune. It runs a little rich now, with the tune.
Mine is stock and I doubt i am any more aggressive than any of you and the best i have got is 26.x MPG
My onboard MPG says 19.x.....
I have never even done a burnout............
My dash counter says 52 mpg..........
My secret - Turbo with different injectors, the computer has no idea what my MPG is
But I average about the same as anyone else I am riding with so I would say mid 20's+
@MiM
You should not dream of getting boosted. That MPG will terrify you, but oh what a feeling.
Now don't get me wrong... City driving and having fun, I really don't care. I do frequent tire spins and traction control light ups in the city...
I just thought it would be better with highway cruising...
Once I do boost, definitely time for a trailer... No more long trips... More like @Bill Martin, rather ride in AC, better suspension (even though I have jri 2 way), and a bigger gas tank!
I for one understand that mentality. I bought it to drive it.
Just finished a 1100 mile round trip to wrench on some slings.
I for one understand that mentality. I bought it to drive it.
Just finished a 1100 mile round trip to wrench on some slings.
Did your bride make that trip with you ?????????? I know in my case rides that long are not even up for discussion when my bride is involved and brother @MiM s bride won't get on interstate in his. We both try to live in the fast lane but are married to speed bumps 
Did your bride make that trip with you ?????????? I know in my case rides that long are not even up for discussion when my bride is involved and brother @MiM s bride won't get on interstate in his. We both try to live in the fast lane but are married to speed bumps
Not this time. I was on a mission.
I for one understand that mentality. I bought it to drive it.
Just finished a 1100 mile round trip to wrench on some slings.
She was not @Bill Martin! She was riding ahead in the Volvo with the 3 girls, faster than I could keep up with! Well, I could have kept up, but would have needed gas a lot sooner... This thing guzzles in 4th gear at 100+mph...
And Trent, I'll be doing that too in July... 15 hours from me to Jim's place... We'll be painting though...
