What MPH do you tow your rig ??

**RicknBobbie** · 08-24-2022, 11:05 AM

We tow between 58-62 mph. At those speeds, on flat ground with no headwind, the truck gets 11mpg. This drops to 9mpg above 65mph. The truck has a 5.3 liter v8 but only a 24 gallon tank, so any drastic reduction in mileage can become a problem, since I carefully plan my fuel stops.

**uwskier** · 08-25-2022, 09:08 PM

Originally Posted by RicknBobbie

We tow between 58-62 mph. At those speeds, on flat ground with no headwind, the truck gets 11mpg. This drops to 9mpg above 65mph. The truck has a 5.3 liter v8 but only a 24 gallon tank, so any drastic reduction in mileage can become a problem, since I carefully plan my fuel stops.

I tried to drive those speeds on this long trip I'm just about done with. I just couldn't do it on a 6 hour day in the saddle that would be 7 hours. I kept it between 66 and 75 depending on wind conditions. LOTS of elevation changes between Denver and Flagstaff. Average for the trip is 8.5 MPG.

Definitely getting a diesel once prices return from Mars. 3 days of driving between 5000 and 8000 feet was a tall task for the 5.3L.

**Stealth13777** · 08-25-2022, 10:02 PM

Originally Posted by RicknBobbie

We tow between 58-62 mph. At those speeds, on flat ground with no headwind, the truck gets 11mpg. This drops to 9mpg above 65mph. The truck has a 5.3 liter v8 but only a 24 gallon tank, so any drastic reduction in mileage can become a problem, since I carefully plan my fuel stops.

That’s interesting. We have averaged 11 lightly loaded and 10 heavily loaded (1500+lb difference over the scales) but are almost always 65-68. Granted, that was with our old smaller trailer. Havnt driven enough with the new one to get a true avg. The big fuel tank is a huge enabler though!

**srigdon** · 08-26-2022, 02:09 PM

Same here whether the speed limit is 70 or even 80 mph.

**ajg617** · 08-26-2022, 04:37 PM

Originally Posted by Jerryr

I like that!

Seriously though, following a semi going between 55-65 mph with my adaptive cruise set I see an immediate 1-2 MPG better MPG. The adaptive cruise maintains the sweet spot distance behind a semi where there’s no buffeting due to “wake turbulence” and there’s less wind resistance.

Birds do this when flying in a “V” formation to reduce energy required to cruise.

Just curious - what is the sweet spot? I tend to follow Semis when I find one that I'm comfortable with - wound up behind same truck on two separate days through upstate NY, OH and IN. But, I don't like losing visibility forward so I am a good distance back - well beyond buffeting - maybe too far back.

I am driving the same route from NH to SD that we did in May but averaging about 1.5 mpg better (10-10.5). I cut my speed down a bit (62-66) and have been following semis (not closely) when able. We are close to 700lbs heavier this trip with more dry camping so not emptying gray tanks as often.

It's interesting that Airbus tested flying their commercial airliners in 'relatively close' formation over the oceans and the fuel savings were not insignificant.

**goducks14** · 08-26-2022, 05:00 PM

"Following semi's" LOL
Last year I was on my way home heading north on I5 in Oregon. I was in the left lane running a touch over 65 mph. Traffic was a little tight and I was just going with the flow. I had two semi's hang behind me for what seemed like 30+ miles. Guess they liked my draft.
FWIW the speed for semi's in Oregon is 60 mph on most all interstates on the west side of the Cascade Mtns.

**timkoenig** · 08-26-2022, 05:16 PM

I guess I am in the minority of not being retired and am usually trying to go 600 miles on a drive day and still be parked before dark. So I have towed at 80-85 out west when the sight lines are long, sunny and dry. The gas mileage was not much different than 70-75. I have really never had the patience to run under 70 on an interstate.

**Jerryr** · 08-26-2022, 05:49 PM

Originally Posted by ajg617

Just curious - what is the sweet spot? I tend to follow Semis when I find one that I'm comfortable with - wound up behind same truck on two separate days through upstate NY, OH and IN. But, I don't like losing visibility forward so I am a good distance back - well beyond buffeting - maybe too far back.

I am driving the same route from NH to SD that we did in May but averaging about 1.5 mpg better (10-10.5). I cut my speed down a bit (62-66) and have been following semis (not closely) when able. We are close to 700lbs heavier this trip with more dry camping so not emptying gray tanks as often.

It's interesting that Airbus tested flying their commercial airliners in 'relatively close' formation over the oceans and the fuel savings were not insignificant.

Sweet spot is dependent on truck speed, wind speed and wind direction. With Adaptive cruise I set the cruise for max distance behind traffic I'm following and watch the instant MPG. If I get buffeting I set to the next closest following distance.

The adaptive cruise radar monitors the distance and adjusts the truck speed to maintain safe distance required at the current ground speed.

If you are getting buffeting you are in the Semi's "Wake Turbulence" which doesn't gain efficiency. You need to be closer.

EDIT": I just found an interesting article. https://en.wikipedia.org/wiki/MythBu...ting_For_Money

Controlled road test: fuel consumption decrease from baseline at 55 mph (89 km/h):
100 ft (30 m) 11%
50 ft (15 m) 20%
20 ft (6 m) 27%
10 ft (3 m) 39%
2 ft (1 m) 28%

**Riverbug** · 08-27-2022, 05:12 AM

Originally Posted by timkoenig

I guess I am in the minority of not being retired and am usually trying to go 600 miles on a drive day and still be parked before dark. So I have towed at 80-85 out west when the sight lines are long, sunny and dry. The gas mileage was not much different than 70-75. I have really never had the patience to run under 70 on an interstate.

You'll get there one day maybe. I wasn't an aggressive driver, no road rage, but always going with the fastest of the pack before I retired. Then one day I realized I wasn't aggravated by slower vehicles, I was driving in the right lane on the freeway, and I wasn't in a hurry to get to my destination. Suddenly, the entire drive experience was different. My wife retired a year later and I would remind her to "drive retired, we don't have a schedule". It took her a bit but she got there too. Now we both enjoy the drive as much as getting to the destination. Not being bound by work constraints on rushing schedules, vacation days, getting here or there between meetings or phone calls, etc.. It's an indescribable feeling of freedom I've never experienced before in my life. You'll see.

**geotex1** · 08-27-2022, 08:30 AM

Like anything else, you have to have the right tool for the job... Going fast, I have those tools, and my favorite is the '37 Coupe...or maybe its the Sedan Delivery...

Seriously, I like two pieces of advice given - don't out-tow your rig and know the sweet spot... With a Cummins powered dually, it is not hard to let it go, but there are two distinct sweet spots with our combination that optimize the mpg and I'm no longer in daily commute mode. I also find myself using the full length of the acceleration lanes to my advantage since racing to speed, something the Cummins and gearing of my truck has no issues with, absolutely eats diesel! Overall, you will always find me within 5mph of the posted speed limit, and we often elect to take the more scenic trail when one is available and can accommodate our combination.