9 - 10 mpg

I'm not deep into fuel saving devices like dice and some others. For one thing, funds have been tight and a lot of those things require a substantial upfront investment with the payoff coming later. I've had a run of investing in needed repairs instead of fuel saving devices. The latter do no good on a parked, broken truck. Regardless, I am doing what is practically free: really working on improving my driving habits and trying different speeds and methods to reduce consumption. Mainly to enable spending later on some of those things that will take it further.

One thing that has proven most effective is driving my boost gauge down. In one of these mpg threads, I think it was semicrazy that posted about doing this and it works. I clipped the quote above because 65 mph is about the point I've found where more speed drives the boost gauge back up, all other things diminished (momentum is stable, no terrain, calm wind, etc).

This past week for me has worked out with enormous deadhead due to some extraordinary circumstances. An unexpected outcome was being able to look back two extremely opposite driving scenarios with an identical load (nothing, just the empty trailer). Trips with enough mileage to really see the extremes.

The first was a run under time pressure. My logbook average was 68 mph. I was working hard to stay at the speed limit (100% interstates), maybe dropping a little under on uphills and letting it ride a little over on downhills. On a few level stretches, I hit the cruise to stretch my right leg and noticed the boost holding steady between 10-20 psi depending on the wind. My mpg was close to 6 on that trip. Yeah it sucked, but I needed to get there on time, fuel cost was not the priority.

Later, another trip without the time pressure. When I turned the key, my fuel level was slightly below 1/4 and I decided to really try milking it as far as I could before stopping for more. After all, if I added even 30 minutes at the end, it didn't matter. To start, that little less than 1/8 tank carried me about 50 miles farther than expected. So I thought I'd take it as far as I could and see what happened. I went hundreds of miles, focusing on keeping the boost <10 psi. Often dropping a gear or two on uphill grades I could have easily pulled in 13th at the posted limit. I did draw a line on not moving slower than the obviously loaded trucks I encountered, so once in a while I'd mash on it a little to not drop back and impede traffic. There were about 100 miles in the trip where I focused less on this due to some heavy rain, then later traffic. Checking the boost on level terrain with the cruise on, it stayed between 5-10 psi. This trip I averaged 7.5 mpg. Logbook average speed was 61 mph. Keeping the boost <10 with my foot resulted in speed maxing out at about 65-67 on level terrain, depending on the wind. IMO the logbook average speed would have been around 64 without the steep terrain and a lot of 65 mph speed limit areas compared to the first.

Incidentally, the low mpg trip was on better terrain going between Knoxville and East TX. The higher mpg trip was through the hills down I-75 from Cincinnati to ATL. This is a 07' T-600 high roof sleeper, 475 C-15 acert, 13 sp, 3.25 rears on lowpro 22.5 pulling an old, heavy 53' reefer. Steer and recap trailer tires reasonably low RR, but a horrible RR on drives (Bandag Megatrek caps). I run the 5th wheel all the way back or one tooth forward due to APU weight, so not any more room to close the trailer gap more due to the other fuel saver LOL. No hubcaps, no trailer skirts or tails, no synthetic lubes, no frictionless bearings, no ecm tunes, no special exhaust, air filters, and stock turbos. With the only fuel saving device below my right ankle, I can get this truck to approach 6.5 mpg with a 79,700 lb scale ticket in my pocket.

I'm pretty confident that with some aerodynamic and friction reducing upgrades, 7.5 mpg loaded is not going to be hard to reach and 8 is achievable. I'm watching these threads with interest, studying what seems to have the most value, or bang for the buck. So far I'm seeing the trailer tail and single drive axle being the most substantial and measured things that catch my attention. Not to short-change other improvements, but the accounts seem to be a lot more objective. Gains certainly exist, but don't seem as consistent.

 

I go as slow as my gearing allows, which is 58 depending on other factors. That is my best mpg. No way 1500 rpm would be good for me.
I see that MVT has lots of different tractors. Do they all have single drive?

 

The fleet trucks all do, those are the blue ProStars. The other brands and colors are owner operators and they are equipped however. Though some of the different colored Prostars are repainted ex fleet trucks with the singles and tag axles. There is another El Paso based fleet called Out West that is using similarly equipped ProStars with single tires and tag axles.

I drive for Muñoz Trucking and all our newer trucks (Volvos) have single tires but traditonal drive axles. Our newer trailers have the skirts and tails though.

 

everybody's truck shows 666xxx at some point and time.

 

They would get even better fuel efficiency if they weren't using the maxxforce engine. Their numbers may be skewed because they are factoring in miles being towed after engine breakdown.

But in seriousness those are impressive numbers. We will be seeing more companies outfitting their equipment like this as fuel prices continue to climb.

 

Could do that. Cut the axles about an inch from the axle flange and pull the drive shaft and go to town. Center section wont be turning. Fill it with oil and go.

 

It won't move with the rear drive axle disconnected unless you lock the power divider. The power divider won't last long locked in full time.

 

all you drivers who are running slow for fuel mileage i think that's great,but please stay right so you dont slow me down.i still like to get out there and stretch it out a bit and as far as my fuel mileage goes 5 to 5.8 is fine with me.ill give up 200-300 week to be able to run as i want.i still make enough money,if i made more i would just give it to that fool we have for president so he can give it away to people who wont work