what speed yields best mpg?

[JFurst]

55 or 60?

[Trick Pony]

Every car is slightly different depending on gearing and where the motor is most efficient. In general though, the lower speed will get you better mileage because wind resistance increases as the square of the speed.

[SS Junk]

Wherever torque peak is...

[mustangguy289]

My dodge ram has the MDS and 2 overdrive gears. 60 mph and 55 mph have the same RPM once it finishes off its shifting and switches to 4 cyl mode. I average 22 MPG at 60 mph on the highway.

Everycar will be different.

[homealone]

There's no telling. Each car will be different. You'll have to find it's sweet spot. For example, my old 86 yielded 28mpg at 68 mph. My 90 likes 60mph. My BMW peaks mileage about 80.

You will have to play and figure it out.

[JFurst]

Truck is a 2011 5.3 silverado crew 2wd
Travel trailer is 26 feet wieghs 6600

[JFurst]

First tank ill do 55 and see

[RWhite]

I had a 2004 F-250 Super Duty pulling a 32 ft. race trailer and, whenever I drove, it was at 60 mph nominally. I got 10 mpg +/-. When my son got tired of us going so slow, he would take over and raised the speed to 65. The mpg lowered to 8 mpg.

[BP]

Whatever speed those city buses are driving at. My Camry does the best at 80-85 mph, which just so happens to coincide with the flat terrain and thin air out in West Texas.

[dville_gt]

Whatever speed those city buses are driving at. My Camry does the best at 80-85 mph, which just so happens to coincide with the flat terrain and thin air out in West Texas.

my car does best around 75mph, it actually gets worse mpg's at 55 or 60 (but then again it is a car not a truck).

[papapepper]

My car does best at 70 MPH.

[Grimpala]

My truck gets 16 no matter what. Dad's on the other hand, gets better mileage the faster you go.

Pulling our trailer with atvs and gear to the deer camp last year it got better mileage in 5th gear vs 6th. He has a 2010 Chevy 3/4 ton with the 6.0 and 6spd trans. The 3.73's kill it in 6th gear, it was lugging something fierce.

Every car is different, and normal math goes out the window when you throw a trailer into the equation.

[46Tbird]

2006 Ram 4.7/auto gets its best mileage at 60-62mph. I can get 23 out of it at that speed. But it drastically falls off when going faster or in stop-and-go traffic so I average about 16.5mpg per tank.

This is all based on the instant mileage sensor on the truck which I've found to be fairly accurate. So far it's never been more than 1mpg off.

[GE]

Warp speed.

[HarrisonTX]

55 or 60?

Wherever torque peak is...

Every car is slightly different depending on gearing and where the motor is most efficient. In general though, the lower speed will get you better mileage because wind resistance increases as the square of the speed.

I would say ALOT more than slightly different.
My fullsize v6 does best at 75mph. At 65, its just making much power, if I can run 75, or 80, it does MUCH better.