Odd Gas Mileage on Trip

[RobertD]

I went on a trip from Texas to Utah to Colorado and back to Texas. Had a great time. And my 23 King Ranch FX4 ran fine. I started with about 3,000 miles on the truck. I hauled a 3'x3'x4' tall crate with a Kamado Joe for my son in Utah that weighed about 500lbs max. On my first day I got 16.5 mpg. I was thinking that the crate must provide much more wind resistance than I thought it should. Disappointing mileage but I was not going to let it get me down. The odd part is the next two days with the sane crate I averaged 23 mpg without changing driving habits. After I dropped off the crate I averaged in the 20-24 mpg range depending on the mountains and city traffic. Except for the first day I got great mileage. I can't figure out why the first day was so far off. Any thoughts?

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[coyotemik]

Elevation change and wind direction can have a huge factor.

 

[Lricaud81]

Maybe the speed limits in the different states as well.

 

[Bryan Simon]

Took a trip to Las Vegas from San Antonio last Oct.
V8/3.31/4x4/no cargo but a suitcase
I am a cruise control user.
Hard pressed for 17 (@80ish) until I got to ElPaso
ElPaso to Phoenix—21
Phoenix to Vegas, about 17 again
Pretty much the same results going back home.
Hills, cruise, 80+, not a good combination

kinda weird because at home on my commutes, I average 20.5-21.5
Rural hiway/freeway

sitting on 19.9 now, but have some actual city time and ac has been on for a couple of months ( not normally an ac user, but a window down guy)

 

[Gutshot]

Set up the dash with the boost gauge, watch boost, when boost comes in, fuel eco drops. Play with the tranny a bit(get yet mind outta the gutter), a gear or 2 less will change the boost to near nothing sometimes.
Learned it here, shared it here.
Good luck
Edit
Also have the instant fuel mileage bar up so you can watch the mpg’s drop while the boost goes up.

 

[RobertD]

All good ideas. Thanks.

I did not think about wind direction maybe I was hitting it head on and did not notice.

The first day with the bad mileage was the most gradual elevation of the trip. Texas is pretty flat overall.

I do usually have the fuel economy bar showing. Not sure how to show the boost gauge. Is this a Forescan thing?

 

[JIMFOUNTAIN]

All good ideas. Thanks.

I did not think about wind direction maybe I was hitting it head on and did not notice.

The first day with the bad mileage was the most gradual elevation of the trip. Texas is pretty flat overall.

I do usually have the fuel economy bar showing. Not sure how to show the boost gauge. Is this a Forescan thing?

Configure the gauges in settings to show the boost guage.

 

[johnhbrandon]

Still, the best way to calculate gas mileage is the old fashion way of filling up the tank, record your mileage, then fill it up again and see how many gallons it took, then compute your mpg. Unless you reset your onboard mpg calculator before the beginning of your trip, the computer will be using old average data which can be misleading. This happened to me on a 1000 mile trip recently when I roughly calculated how far I should be able to go on a full 36 gallon tank on relatively flat ground. Using 21 mpg average and only 34 of the 36 gallons, I calculated I would be able to drive approximately 714 miles on that tank. But before resetting the mpg calculator and filling the tank, it showed a distance to empty of only 600 miles. Indeed, I did drive over 700 miles on that tank of gas.

 

[Dizz]

I get crazy mpg as well difference between a head wind and tail wind can easily be 4mpg I think
My lie-o-meter is almost always 1.5-2mpg in wrong direction
Strange on my 2014 Civic it’s always right on money

 

[parkerdog]

Sometimes it's best to keep it simple. Maybe a tank of bad gas?

Even your regular station can get a different batch.

 

[kevdog0710]

I drove 1000 miles pulling my camper this past Thanksgiving. MPG varied tank to tank. I definitely got bad fuel on 1 fill, ended up below 7 mpg. Best I did was north of 12 mpg.

 

[RobertD]

Sometimes it's best to keep it simple. Maybe a tank of bad gas?

Even your regular station can get a different batch.

I didn't think of this. Thanks.

 

[RobertD]

Still, the best way to calculate gas mileage is the old fashion way of filling up the tank, record your mileage, then fill it up again and see how many gallons it took, then compute your mpg. Unless you reset your onboard mpg calculator before the beginning of your trip, the computer will be using old average data which can be misleading. This happened to me on a 1000 mile trip recently when I roughly calculated how far I should be able to go on a full 36 gallon tank on relatively flat ground. Using 21 mpg average and only 34 of the 36 gallons, I calculated I would be able to drive approximately 714 miles on that tank. But before resetting the mpg calculator and filling the tank, it showed a distance to empty of only 600 miles. Indeed, I did drive over 700 miles on that tank of gas.

I filled up the day before and zero'd the A trip and only went a few miles home.

I tend to zero the A with every fill up and zero the B with every oil change.

I did get a couple 700 mile tanks of gas on this trip. I don't normally go that low ( it keeps the fuel pump cooler to keep more gas in the tank) but the price of gas varies so much from state to state and town to town. I just couldn't pay above $4/gal...

 

[Gros Ventre]

Headwind vs Tailwind... makes a real difference. even a somewhat light head wind saps MPG.

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