I posted results from a recent trip on a different forum and got blasted for them. Maybe I'm calculating it all wrong and someone here can explain it to me. This was my first big haul with this truck and trailer. I used to tow with my 99 but got only about 14mpg hauling a car hauler.

I have the truck in the sig below, hooked up to my 24' gooseneck deck over (pic below). When I unloaded at the dump, truck and trailer came in at 5,750kilograms so 12678lbs according to an online calculator. On top of this I had an 88 Camaro which I estimated to be 3500lbs with an extra tranny. 6 46" military tires which I was told were 225lbs each, 5 37" tires which I was told were 125lbs each and 2 rockwell steering axles which I was told were 750lbs each. That makes the total weight 19653 loaded. I have a 90 gallon in bed fuel tank. I drove from Buffalo, NY to Akron, OH to Fayetteville, NC unloaded and then from Fayetteville, NC back up to Buffalo, NY loaded. I left Buffalo with both my stock tank and the 90 gallon tank full. I pulled back into Buffalo after 1557miles according to my odometer and the main gas guage just started to move. It always leaves some in the 90gallon because the gravity feed plug is on the side of it. Since the main tank moved I estimated that I used 90 gallons of gas total. 1557miles, 90 gallons of gas is 17.3mpg. Right? I also set the cruise on my truck around 75mph and stopped only once on the 11.5 hour trip home. 11.5 hours of driving, 30 minutes for lunch. I left Fayetteville at 10:00am and pulled into Buffalo at 10:05pm. I stayed in the left lane on the highway, even up through the mountains and the cruise never varied. I'm getting blasted because I'm being told it's impossible ... I don't really know what else to say, unless i'm looking at this all wrong. I do normally get between 1800 and 2000 miles from my inbed tank before I notice the guage move and have to go fill up without the trailer hooked up. I did get my speedo corrected to match the new tires and I also drive with GPS telling me exactly how fast I was going. Can someone please explain if I'm doing something wrong with my calculations?

Oh yeah .. I had the Smarty on Stock Injector/Stock Turbo SW#6 and the TST on 3/1 with fuel pressure on 2, EGT set to 1400 (which I never even went over 1300). Please help me understand.

 

This is the route I took which was 1506 miles but I also had to run to the place to get the tires while in Fayetteville and go to the loading dock to load the car, and detour off the highway to get lunch on the way home.

http://maps.google.com/maps?f=d&hl=e...=UTF8&z=6&om=1

 

With my truck, anyway, I can drive a good ways before the fuel gauge moves...

I would think refueling might give a more accurate measure of how much you burned on your trip...

 

I can drive almost 200 miles sometimes before the gauge moves.

Even if you used 10 or 15 gals more, you still did good @ 14.8 MPG.

I don't usually get that unloaded!

 

I was told to go refuel by another friend and it was a little more than I expected. I just did it at lunch, 1660 on the odometer and 100.8 gallons to fill it so the trip was really 16.46 mpg with 60 of the 1660 being empty truck.

It is that easy to calculate right? Miles/Gallons = MPG?? I'm an engineer and I do believe it's that simple but maybe there are factors I'm not taking into consideration or something.

 

seems like your doing it right to me.......wish I could get some mileage like that

 

You did the math right. That's really good milage...

 

The sweet spot for my truck seemed to be about 75 mph. If I dropped below 70 then it started to studder and the boost guage would bounce around and the turbo barked a lot. Nasty sounds that made me think I was going to need a new turbo when I got home. This only happened a few times when someone pulled out in front of me going a lot slower than i was on a hill.

At one point during the trip I had a Powerstroke with a two horse trailer come up behind me fast so I got in the center lane (still doing 75) and when they were beside me the driver and passenger just smirked. He then pulled in front of me and started to slow as the climb got longer so I pulled back into the left lane and got on it. Passed him uphill at about 85mph and it took nothing for the truck to get from 75 to 85. It just got me all nervous about going that fast with the trailer on the back. He never caught back up.

Usually empty around town i would go about 1800-2000 miles before my guage moved and I always thought it was about 90 gallons so i figured I was getting between 20 and 22 mpg but I never really payed attention when filling up because it made me sick to see it go over $350. lol. I guess I'm really getting about 18-20 mpg unloaded. I'm going to start paying more attention to exactly how many gallons it takes to fill it after the guage moves.

Edit: By "around town" I just mean not going over the road to another state. Not driving only in a city or something. A lot of my local driving is highway driving.

 

Is your speedo re-calibrated with the Smarty for those tires? If not you actually went further

 

That is excellent mileage. If you say you got it I don't doubt you... but with those tires, as opposed to stock, you are pushing a lot of rubber and I see 2 mpg less myself with a similar setup. With my weight, I usually tow around 12 mpg. I have 8K trailer.

 

I had my speedo corrected at the dealer before I got my Smarty but according to my GPS it's dead on. I gave them the revs per mile that Nitto posted and they just put it in.

As for the mileage .. this was my overall average, going down with the trailer empty an then back full. With the trailer empty I don't notice much difference in the truck pulling from a stop. It's hard to believe there is 5500#'s of trailer behind me. I'd kind of like to weight the trailer by itself because it says it's 5200# but I added a winch and extra battery. It just seems lighter behind the truck. I'm kind of figuring if it was 16.46 overall I probably got around 18 down there and 14 back. Just complete guesses.

 

Well I guess the Camaro adds to the aerodynamics of the trailer. That's some darn good mileage! I'd get 17-18 mpg on the highway, empty, babying it, going below 65 mph. What gives?

 

17-18 was pretty typical for my 99 standard cab long bed ram with intake, exhaust, injectors, torque dog and 4.10's with 35's.

This truck gets much better economy just day to day driving with the mods I've got on it. I don't go by my overhead because I've heard they are innacurate but I do look at it now and then to see trends when driving. On flat highway between Buffalo and Rochester, at 65mph (the speed limit), it sits at 20.8mpg, at 70 it jumps to 21.1 and at 75 it jumps to 22.5 and at 80 it drops back to 20.4. I did 20 miles with cruise on each setting. Changed speed and then reset it again. I was just curious as to what it would think the change was. That was when I determine 75 was my sweet spot.

This was all just testing it to see where I would be best with the empty trailer on the back. This run out to Rochester I had the trailer on the back empty and then hauled a load of material back to Buffalo from a job site and didn't pay attention to it.

 

when pulling a trailer like mine ,mileage will not be good because of wind resistance, you trailer setup looks to be pretty clean. so weight is not a large factor unless you are in the mountains..... my fiver is like a large sail,my best mpg is 12 . mostly i get around 9..... it doesn't matter too much how fast i drive

 

I could only imagine what it would be like to tow a camper behind it. I always thought it would be like riding a bike with a parachute on. lol. I want to get one someday though.

I'm topping off the tank tonight so I can guage my unloaded mpg since I am leaving tonight for another trip (for work) and it will be 486miles total trip and all of it in Canada so I'll be setting the cruise at 75 again and seeing what it takes to fill it back up when I get home Saturday.