mpg gauge reliability

[Collin]

Hi everyone, I just got my truck and I'm concerned about the mpg monitor's reliability.

I'm not too concerned if it's not accurate, but I'm hoping it's off by a reliable amount.

I reset it each trip. One trip I'll drive like an old granny-slow acceleration, stick to speed limit, coast to stop signs etc. and get best 12.9 mpg. But if I drive like a normal person with a Hemi, it says I get 11.5 mpg.

Are these fuel consumption gauges reliable enough to give me any useful data?

 

[Stangshcky12]

Unfortunatly they aren't very reliable
Theyre getting closer but they're still off 1-2 mpg a tank

 

[quietpeen]

welcome to RF. The best reliable way is to calculate it yourself

 

[HemiBabe]

Mine has always been pretty accurate when I calculate it myself

 

[infernoredram]

Mine is pretty accurate as well. I just finished a whole tank (80% HWY), and got reasonably close to my monitor. The gauge was reading 22-24 on the hwy, and I just did a hand calc getting 22.3...but I have baby tires, no lift or level, no extra weight, and I drive like a grandma.

 

[TexasRammer]

Mine has always been pretty accurate when I calculate it myself

same. calculate it yourself to check though. some are pretty accurate and some can be way off, not sure why though...

 

[02blkram47]

If you have a smart phone download "fuel log" its free and you will see that the gauge is off by nearly 1 MPG. The great thing about the app. Is you can still calculate with partial fill ups and you get stats like how much money you spend by the day, mile, month,year on fuel. 2000 rpm is my sweet spot. If I drive too long over 2k my mileage suffers alot. I was averaging just under 10 mpg when I was accelerating hard and keeping above 2k. I've now been getting up to speed slower and keeping it around 2k and I'm now seeing 12.5-13.0 mpg.

 

[truckin151]

I never go off the overhead mpgs. I've tried this on mine just to see how accurate the thing was, filled up a tank of gas and reset the computer. Drove the exact same rout, about a 25mile drive and reset the computer in-between drives. Same speed same day etc etc. Each trip the MPG number changed sometimes it was higher some lower and it went back and forth usually off by about 1-2 mpg from the original. Per pen and paper math it's roughly 1.4mpg off on the high side.

 

[MADDOG]

They tend to be adaptive. Reset it to zero and watch it as you drive. You'll see it change, change again, then change some more. You are better off calculating your MPG the old fashioned way...miles driven divided by gallons consumed.

 

[Mr_Nacho]

Not to get off topic, but has anyone ever had their outside temperature jump to -40 on the display? Mine only does it once in a while and for about a minute or two when it does. I had always been a little skeptical about the mpgs readout though.

 

[smiley]

Hi everyone, I just got my truck and I'm concerned about the mpg monitor's reliability.

I'm not too concerned if it's not accurate, but I'm hoping it's off by a reliable amount.

I reset it each trip. One trip I'll drive like an old granny-slow acceleration, stick to speed limit, coast to stop signs etc. and get best 12.9 mpg. But if I drive like a normal person with a Hemi, it says I get 11.5 mpg.

Are these fuel consumption gauges reliable enough to give me any useful data?

Sounds pretty real to me haha. I find that mine is pretty close when I compare to hand calc like stated though it will always average so the more miles driven the more accurate but then that is assuming some consistent paths. If you take a different way to work each day it will never be able to average it perfectly. Like for my job I could go about 3 main ways and all have various speeds and settings and all take 11 minutes roughly.


$miley

 

[Collin]

Thanks for the help guys.

I'm going to have to form a baseline myself to see how much I can depend on the gauging. I want to get better than the 12 EPA estimate when I'm driving like an old woman. I think the nobby tires I just put on it will make it the truck a little less efficient--but I have no way of knowing how much less.

I drive the same route pretty much. I've been only trying to measure the parts where I usually don't have to contend with traffic. Coasting down a 2 mile hill at 25 mph will **** people off fast...but it only seems to get me less than a gallon a mile of savings over normal driving. That can't be right.

For me, the temperature gauge is usually pretty good. I drive by a bank with a temperature display and my display is usually the same. Sometimes a couple degrees off, but that could be explained by the truck being driven and a bank just taking a local reading.

 

[garner]

Mine in the R/T and in this new truck are pretty accurate. Same with the ones in my 06 mustang and 2011 genesis. Never had an inaccurate one

 

[Stangshcky12]

Lol they didn't get the nickname lie-o-meter for no reason especially the ones in 3rd gens
Like I said they are getting better but there still plu or minus 1-2 mpg
When your gettin 12-14 mpg that's 15-20% error

 

[Collin]

Update:

Doing the same route, I was able to bump it up to 13.2 by getting better at coasting and slow accelerating. If that's accurate, that's still not great.

Maybe the oil change I'm going to do will help a tiny bit.

And if I clear it before accelerating to a 50 mph highway, it says I get about 1.2 mpg. Which I thought was hilarious

 

[Stangshcky12]

That's about right for an 04
You can check this out to compare
2004 Dodge Ram 1500 MPG Reports | Fuelly

 

[02blkram47]

Since using the Fuel log app I've had 6 fill up including 2 partial fill ups and I have a best fuel mileage of 13.08 and worst of 11.9 with an average of 12.27. this is with a total travel of 856 miles with 90% of it in town driving. these calculations are about 1-1.5 mpg better than what my truck tells me I'm getting.

 

[Collin]

Since using the Fuel log app I've had 6 fill up including 2 partial fill ups and I have a best fuel mileage of 13.08 and worst of 11.9 with an average of 12.27. this is with a total travel of 856 miles with 90% of it in town driving. these calculations are about 1-1.5 mpg better than what my truck tells me I'm getting.

How much did you change your driving to get 13?

 

[RumbleBee1385]

I have found that my MPG meter is with 1 or two MPG's when reset at every fill up. I also use an app on my android phone called ACAR that tracks gas fillups, partial fillups, maintenance schedules, costs, has charts and is very customizable. I have been using it for years. Great app!!!

 

[Collin]

Update:

After the oil change, I'm seeing 15 (14.9) mpg on the same route.

That's a pretty good boost, if that's accurate.