Another silly fuel economy post

[volvite]

That sucks.

[doctahjones]

I found, maybe it's due to the diff swap, but my speedo is dead nuts on so I have since stopped adding for the larger tires. Which is bad because well, MPG's aren't so great.

hum, strange since the speed sensors are between the diff and wheel right?

[disallow]

At stock size, your speedo reads too slow. So by changing the tire size and gearing, you are probably correcting it.

Check you vehicle speed with GPS to validate, though there is an error factor there as well.

[doctahjones]

At stock size, your speedo reads too slow. So by changing the tire size and gearing, you are probably correcting it.

Check you vehicle speed with GPS to validate, though there is an error factor there as well.

in general i would agree with you disallow, but if the speed sensors are between the diff and wheel, changing diff gears shouldn't have an effect on the speedo.

now if the speedo is in the transmission (was i was used to in older cars) then yeah, changing diff/gears for sure will 'level out' the speedo (and reported mpg)

[NmexMAX]

That's right, they're on the hubs/axle shafts.

My tires are 33.1" Using GPS and also for giggles those radar readouts the cops put out both verify with the dash speed.

At stock size, your speedo reads too slow. So by changing the tire size and gearing, you are probably correcting it.

Check you vehicle speed with GPS to validate, though there is an error factor there as well.

in general i would agree with you disallow, but if the speed sensors are between the diff and wheel, changing diff gears shouldn't have an effect on the speedo.

now if the speedo is in the transmission (was i was used to in older cars) then yeah, changing diff/gears for sure will 'level out' the speedo (and reported mpg)

[disallow]

in general i would agree with you disallow, but if the speed sensors are between the diff and wheel, changing diff gears shouldn't have an effect on the speedo.

now if the speedo is in the transmission (was i was used to in older cars) then yeah, changing diff/gears for sure will 'level out' the speedo (and reported mpg)

Yep didn't know about the sensor location, that makes total sense.

But the tire size is for sure a factor. When I ran 265/75/16s, my GPS speed and speedo speed were an exact match. Now that I have 265/70/16s they are not, and are about 3-5% off.

Makes a big difference when calculating fuel economy... What are the real numbers dammit?!?!?

[leadpig]

At stock size, your speedo reads too slow. So by changing the tire size and gearing, you are probably correcting it.

Check you vehicle speed with GPS to validate, though there is an error factor there as well.

Mine's the opposite. 75 on the speedo is 71-72 by GPS, which if I'm thinking right means I'm not going as far as the odometer says, so my fuel economy is worse than it is already. And I've only done 15800 miles instead of 16500 and so my warranty will run out sooner than it should!

Or are the miles and the speed measured separately?

[disallow]

When I have taken the time to check, there seems to be a directly linear relationship to distance travelled vs how fast the vehicle thinks it is going.

I would have that checked!

t

[leadpig]

When I have taken the time to check, there seems to be a directly linear relationship to distance travelled vs how fast the vehicle thinks it is going.

I would have that checked!

t

Well, in a bit of procrastination-driven googling, it seems that in US an acceptable inaccuracy is up to 5 % (I'm at 4), as long as it is over. Reading slower seems a universal no-no, so manufacturers generally set vehicles up to overestimate a bit. GPS also has its wobbles, but is generally closer to 1%. Of course all that came off the interweb, so who knows...

[FLiPMaRC]

According to the gauge under the speedo, 350 honest!

My gauge and DTE display are pretty accurate as well. The DTE is conservative by a factor of a couple gallons but that's quite normal. My wife's Acura is far more conservative on the miles to empty.

I've been getting in the 19mpg range lately. Today I have 309 miles on this tank and DTE is showing 45 miles to go. I'll fill up when I get back home which will put me at 335 miles and I'll pump 17-18 gallons.

I've gone 40 additional miles AFTER the DTE hit's zero (or **) and still had a gallon in the tank.

So for the sake of argument....what's your actual mpg if you divide miles driven by gallons pumped?

Welp I just did a 1,500 mile road trip to Ontario, Canada last week. It was my first real road trip with the Pathy. The DTE just kept going up and up every time I filled up. 384 was the highest It really likes the highway driving. I was running 70-75mph most of the time.




Screen shot of my Mileage history App on my phone. I tried my best to convert from Canadian dollar to US dollar and from Liters to US gallon (3.78 liters NOT imperial gallons).




And this one was a fluke I think. I was on a stretch of road where I was running only 50mph for a good 45mins.

[semaj]

For instance, today with DTE showing 29kms and my gas gauge right at the bottom, I filled up. The truck took 64L. It has an 80L tank. But the gauge showed it was right empty. (traveled 430km on that much fuel, which equates to 14.8L/100km or 15.8MPG)

I came here looking to see if this was normal

My gauge was nearly on E, DTE says 30km, filled up and it only took 64L too! But my mileage seems correct as well. I guess I will stop worrying.

On a recent road trip to Portland, OR I was getting great mileage and the DTE got as high as 572km

[doctahjones]

And this one was a fluke I think. I was on a stretch of road where I was running only 50mph for a good 45mins.

going downhill with a tailwind right?

i can get briefly get similar numbers if i fill up in a mountain town and coast back down to denver.

[FLiPMaRC]

I would be happy with just a constant 20mpg.

Now that I'm back home and on my normal mixed city & highway driving, I'm getting my normal 17-18mpg.

[CPLTECH]

I grew up thinking that I could get better mileage by not using cruise. However, by using the ScanGauge2 & monitoring “instant MPG” I am finding that cruise is a good thing since the gas pedal on the PF is so touchy. So other than not using it going up hills, I am using cruise a lot more.

[DanJetta]

Wanted to see how high I could get it. I think this is the top.