Wonky mileage change

[benenglish]

This is weird.

My truck, a 2002 F150 with the base V6, gets 13-14 mpg. It always has except times when I'm going a long distance at a steady 55 mph when it might creep up to, at most, 18 mpg. If I treat it rough in around-town, stop-and-go traffic, it might drop to 12 mpg.

I reset my trip odometer after fill ups and calculate mileage if I fill up again at the next gas stop.

I filled up today, ran the numbers, and for my last tank I got a touch over 20 mpg. This entire tank was around town driving and I can't think of anything I did differently.

I've had vehicles suddenly get worse mileage when something was wrong but I've never experienced this sort of sudden improvement.

Any theories?

 

[Otto_Mation]

Not sure if this is the issue that you are seeing but, my Tacoma gets better mileage in the city than on the highway. That said, I am rolling faster than 55 on the highway.

 

[Eastexasrick]

Our 2004 Ford Exploder with the same V6 gets a similar increase, not quite as big, but similar when I run ethanol free gas in it.

 

[benenglish]

Our 2004 Ford Exploder with the same V6 gets a similar increase, not quite as big, but similar when I run ethanol free gas in it.

I almost always get my gas at the same place so if this is the explanation, they must have gotten a wrong delivery.

 

[dsgrey]

Possibly the pump cut off sooner than normal? I assume you have a 20+ gallon tank, could have cut off 1 or 2 gallons sooner than normal but still shows full.

 

[Bozz10mm]

Gas companies switched to Winter formula fuel?

 

[benenglish]

Possibly the pump cut off sooner than normal? I assume you have a 20+ gallon tank, could have cut off 1 or 2 gallons sooner than normal but still shows full.

There might be something to that. Hopefully my next fill-up will shed some light.

 

[msharley]

This is weird.

My truck, a 2002 F150 with the base V6, gets 13-14 mpg. It always has except times when I'm going a long distance at a steady 55 mph when it might creep up to, at most, 18 mpg. If I treat it rough in around-town, stop-and-go traffic, it might drop to 12 mpg.

I reset my trip odometer after fill ups and calculate mileage if I fill up again at the next gas stop.

I filled up today, ran the numbers, and for my last tank I got a touch over 20 mpg. This entire tank was around town driving and I can't think of anything I did differently.

I've had vehicles suddenly get worse mileage when something was wrong but I've never experienced this sort of sudden improvement.

Any theories?

Yes.

Good gas...

My F 350 (460cid, 4 speed, 4:11 gear) gets more power, better mileage on ethanol free gas..

Runs like it has three more cylinders and mileage goes from 8 or 9mpg to 12 or 15!!mpg!!

If? you have a head gasket starting to go (ruling out real gas/good gas by accident at the fillin' station)...

WATER INJECTION greatly improves power/fuel economy (does not matter if it is coming from the cooling system) LOL

50 to 75% increase in fuel economy with water injection...20 to 30% increase in power.

 

[Byrd666]

Might be a different mix in the gasoline. If too much of the premium was ordered and won't fit in that tank, it's dumped into the next flavor down, and so forth. Used to get that occasionally in my 1/2 ton Dodge. Or when I didn't get the corn liquor type gas.

 

[vmax]

Gas companies switched to Winter formula fuel?

The refineries have been in the process of changing to winter blend gasoline and diesel for a few weeks.
Not offering an explanation on the milage but just backing up your assumption about the switch

 

[oldag]

Wow. Undersized engine? All my work pickups and personal pickups do better than that on the highway running 80 mph.

 

[Txhighlander]

Might be a different mix in the gasoline. If too much of the premium was ordered and won't fit in that tank, it's dumped into the next flavor down, and so forth. Used to get that occasionally in my 1/2 ton Dodge. Or when I didn't get the corn liquor type gas.

Shouldn't happen that way but it does. I never did it when I hauled fuel but I knew those that did.

 

[Tnhawk]

Gas companies switched to Winter formula fuel?

Every Spring/Fall, I have a seasonal change of 2-3 mpg due to the changes made in Summer/Winter formulas.

 

[Big Dipper]

Accelerating from stop light/signs uses up lots of fuel. Any chance you got lucky and hit lotsa green lights?

 

[benenglish]

Accelerating from stop light/signs uses up lots of fuel. Any chance you got lucky and hit lotsa green lights?

That makes as much sense as anything else. But I'm doubtful that I got lucky for every light for weeks.

 

[prisondoc]

This is weird.

My truck, a 2002 F150 with the base V6, gets 13-14 mpg. It always has except times when I'm going a long distance at a steady 55 mph when it might creep up to, at most, 18 mpg. If I treat it rough in around-town, stop-and-go traffic, it might drop to 12 mpg.

I reset my trip odometer after fill ups and calculate mileage if I fill up again at the next gas stop.

I filled up today, ran the numbers, and for my last tank I got a touch over 20 mpg. This entire tank was around town driving and I can't think of anything I did differently.

I've had vehicles suddenly get worse mileage when something was wrong but I've never experienced this sort of sudden improvement.

Any theories?

Sent from my SM-A536U1 using Tapatalk

 

[benenglish]

Undersized engine?

I think so. I've been told so by lots of folks who seem to know about that drivetrain. I even figured that's the reason the truck had a half-dozen owners before I bought it. Who wants an underpowered truck that.sucks gas so prodigiously?

 

[popsgarland]

In my 2013 1/2 ton Chevy truck, I get better mileage when I was traveling than around town
because of no stop and go at signal lights, stop sign or stop and go traffic. Also going a steady
speed, my engine would drop from 8 cylinders down to 6 cylinders.

 

[ZX9RCAM]

88 cylinders, damn!

 

[Txhighlander]

88 cylinders, damn!

Wow that is a big truck engine