Gas Mileage

[Kyle Keller]

Yes i know its not a prius and gonna get 35 mpg on the highway but I am just curious as to what other people get on the highway driving.



I average about 16.5-17mpg on the highway at 80 MPH, which with 4.10 gears is about 2800RPM. I've got 31x10.5 tires, a grille guard (don't know if this hurts aerodynamics), MAC intake, factory tonneau, exhaust, 73k miles.



This about average?

 

[David Ponder]

I have a 2001 4X4, 4:10 gears.



At 75 MPH I get 17 or so mpg.

If I can keep it to 65 MPH, I have gone over 20 mpg.

 

[Robert Caffyn]

Around town, 15 to 15.5. Highway, maybe 20-21. I've got the V8, it loves to drink fuel. Bob

 

[Kyle Keller]

I'd take a V8 with 20mpg over a sissy V6 with 17mpg any day!

 

[Richard L]

Kyle,

Trying to maintain 80 MPH is your biggest problem. When you are trying to maintain a speed higher than the surrounding traffic, you will constantly have to slow down and speed up, and that's what's eating your gas mileage.



I live in Texas where the usual speed limit on interstates and highways is 70 MPH. I used to drive between 70-75 with both of my Sport Trac's and easily got 23 MPG when nobody was on the road. When traffic picked up I had to drop my speed closer to 68-70 MPH to continue to get 22-23 MPG.



What eats the gas is accelerating back up to speed after slowing down for slower traffic. If you had a ScanGauge or other trip computer that gives instantaneous gas mileage readouts, you would see your mileage drop about 5 MPG or more each time you slowed to 65-70 MPH and then speeded back up to 80 MPH. That is especially bad on gas mileage when you drive a heavy vehicle like a 4X4 Sport Trac.



Most low mileage is caused by poor driving habits. Slow down to the speed of the surrounding traffic or even a 1-2 MPH slower, get in the right lane and stay there. Just try it for a few days and see the big improvement in gas mileage....If you don't go insane first...:grin:



...Rich

 

[Kyle Keller]

Yeah thats true Rich but usually when i'm doing 80 i am by myself on the interstate with cruise control on and just switching lane for one car at a time and not having so slow down and speed back up. If I am in traffic I slow down and keep a constant speed but when Im by myself I'll do 80 in a 70 with the cruise on. Gas mileage isn't killing me I'd rather do 80 and get 17mpg than 75 and 17.3mpg it's not that big a deal to me I just wanted to make sure nothing is wrong because even when it does seem like i'm lighted footed and taking my time on trips I still only end up with like 17.5mpg. The 4x4 4.10 doesn't help AT ALL.

 

[Jim Johnson]

In mostly rural driving, my 4WD ST averaged 18 MPG for the first several years. Now that it has over 130k miles on the odometer, it's closer to 17 MPG.

 

[EddieS'04]

410 gears, stock tire diameter, and sct peformance tunes. 400 miles highway, I got 18.7mpg @ 85mph.

 

[Bill Koonce]

Ditto to what Rich said. If the road is flat and relatively empty, I can get an average fuel economy up to 23 MPG, maybe more. That's with the cruise control set to 65 MPH. If I get into traffic, the necessary WOT sprints past road hogs, and 75 MPH cruising speeds necessary to keep aggressive drivers from attacking from the rear brings the average just below 20 MPG. That's a stock '07 4x4 (3.55:1 gears), BTW.



Remember that above 35 MPH, aerodynamic forces rapidly become the greatest consumer of engine power. Since the ST has aerodynamic properties of a brick, slowing down on the highway has a dramatic effect on fuel economy.

 

[Robert Gay]

Close to 20. Depends on a number of factors.

 

[Richard L]

Kyle,

Your original question implies that your mileage of 16.5-17mpg is for a constant 80 mph speed?? That would be very good mileage for that speed in a 4X4 Sport Trac.



I cannot conceive the notion that you can drive for any length of time at 80 MPH on the Interstate in the Marietta, GA area (basicly a suburb of Atlanta) without encountering other slower moving traffic that will require you to slow down and speed up, unless you are driving very early in the morning.



Assuming you are calculating your gas mileage after a fill-up, you cannot possibly assume that you averaged 80 MPH for that whole tank of gas. Your average miles per gallon includes all the stops, starts, slow downs and accelerations during that whole tank of gas. Even if you do most of your driving on the Interstates at 80 MPH, variable traffic conditions will prevent you from maintaining that speed for any length of time and you may find that your average speed was actually less than 70 MPH.



...Rich