Gas mileage

[Idea]

We are on our way home from our first airstream trip. We had two weeks to travel from Greensburg Kansas to Yellowstone. A big surprise has been how well our 2008 Chevy 1/2 ton 4wd has pulled the trailer and we have averaged 12.5 mph.

[moosetags]

That's very good mpg. WE have towed a 25 foot Airstream for many years with a 3/4 Suburban. We have always averaged about 10.5 mpg while towing.

Brian

[ckottum]

That mirrors our Ram 1500 towing experience. Gas mileage is entirely dependent on wind direction, terrain, and speed. Mostly.

In rolling hills we do best selecting a transmission gear that keeps it from shifting up and down to maintain speed, especially in cruise control. For us that is 4th gear (of six) which is a 1:1 ratio, which is also most probably the most efficient of the gear ratios in the transmission, so we leave it there most of the time. Unless there are good tail winds or long downhill grade.

The transmission also has downhill braking assist mode that may benefit efficiency. When going steeper downhill grades in "Tow/Haul" mode, touching the brake will advise the transmission to shift down automatically to try to maintain that speed. That allows engine braking, rather than running gear braking which may waste fuel.

Yes, this size truck is an excellent match to mid-size Airstreams. We are fortunate to have an Airstream and are thankful for it, box-shaped trailers are not nearly as efficient or pleasantly towable by trucks of this size.

cheryl

[Tincampers]

3/4 ton Suburban here with 25' FC and we get between 9.9 and 10.0...

[Idea]

We are pulling a 2004 25' and our vehicle does have the trailer pulling mode.

[BoldAdventure]

We average about the same, except for going up hill, then it blows, but I suspect this is the case for everyone, diesel and gas. More power required to overcome gravity.

[Lance M]

Originally Posted by Idea

We are on our way home from our first airstream trip. We had two weeks to travel from Greensburg Kansas to Yellowstone. A big surprise has been how well our 2008 Chevy 1/2 ton 4wd has pulled the trailer and we have averaged 12.5 mph.

Is this from the trip computer, or hand calcs?

[cwf]

2012 Duramax 4x4 Crew cab 54k miles.

15-17mpg hwy no load
8.5-10.5 towing 34' triple axle. (when first towed, we consistently had 12-15Mpg...so truck has a problem, I think)

[J. Morgan]

It might be that the vanes on the turbo are stuck, or the case of the turbo case has heat cracks locking the variable vanes in place.

Been there done that...

[cwf]

J. Morgan.. Can't send PM till you flush some of the flotsam and jetsam.

Tell me more...

[mandolindave]

When I had my oil change I also got a new air filter. It appeared to me that I started getting a few more MPG. Could that be ?

3/4 ton van with 4.3 liter engine. 20 footer 3000 lbs

16-19 normally…12 towing

[BoldAdventure]

A dirty enough air filter can mess up MPG for sure.

[J. Morgan]

The VVTs (variable vane turbochargers) often become gunked up with soot from the EGR, causing the vanes to stick to the case and not open and close properly.

I also had one where the cast iron part of the turbo case cracked and would not allow the vanes to move.

We had to fix this on one of my duramax trucks a couple of months ago.

The turbos are easy to clean and rebuild for about $100 in parts, but the turbo is challenging to get loose from its mounted position.

This may not be your problem, but I have had to clean these turbos several times on both DMaxes and Powerstrokes. (Same turbo)

[55AS]

Originally Posted by Idea

We are on our way home from our first airstream trip. We had two weeks to travel from Greensburg Kansas to Yellowstone. A big surprise has been how well our 2008 Chevy 1/2 ton 4wd has pulled the trailer and we have averaged 12.5 mph.

That trip would take a very long time at 12 MPH

[moosetags]

Originally Posted by cwf

2012 Duramax 4x4 Crew cab 54k miles.

15-17mpg hwy no load
8.5-10.5 towing 34' triple axle. (when first towed, we consistently had 12-15Mpg...so truck has a problem, I think)

You may have a truck issue. We have a 2011 3500 Duramax crew long bed with 81,000 miles on it.. We tow a 25FB (7400#) and carry a 3,200# truck camper in the bed. We consistently get 11.5 mpg towing and hauling over 10,000#.

Brian