Which MPG is correct?

Smile-n-Nod · #1 07-03-2012, 04:38 PM

I've driven my shiny, new 2013 Elantra about 3000 miles now and am getting some confusing fuel economy numbers.

When I filled up last week, I reset the AVG MPG display and left it untouched for the entire tank. After 340 miles of driving, the display read about 35.5 mpg. When I filled up the tank and did the math, however, the actual fuel economy was only about 32.1 mpg.

Anybody know why?

diamondlarry · #2 07-03-2012, 04:48 PM

Quote:

Originally Posted by Smile-n-Nod

I've driven my shiny, new 2013 Elantra about 3000 miles now and am getting some confusing fuel economy numbers.

When I filled up last week, I reset the AVG MPG display and left it untouched for the entire tank. After 340 miles of driving, the display read about 35.5 mpg. When I filled up the tank and did the math, however, the actual fuel economy was only about 32.1 mpg.

Anybody know why?

I always go with the calculated at-the-pump numbers. Since I always completely top off the tank all the way to the top, I know that if I went x miles and put in y gallons, the result has to be accurate despite what the display reads. My $.02 worth. YMMV.

Smile-n-Nod · #3 07-03-2012, 04:54 PM

If the pump mileage is correct (and I realize that it probably is), my 32 mpg is pretty disappointing. I accelerate slowly, coast when possible, have my tire pressure at 44 psi, etc., etc., etc., and if I can't even match City mileage, it appears something may be not quite right with my vehicle.

ItsNotAboutTheMoney · #4 07-03-2012, 05:13 PM

Quote:

Originally Posted by Smile-n-Nod

If the pump mileage is correct (and I realize that it probably is), my 32 mpg is pretty disappointing. I accelerate slowly, coast when possible, have my tire pressure at 44 psi, etc., etc., etc., and if I can't even match City mileage, it appears something may be not quite right with my vehicle.

Define "accelerate slowly" and "coast". If it's an AT you'd want brisk acceleration up to speed and then NICE-ON instead of coasting unless you specifically have spare momentum you need to discard.

Smile-n-Nod · #5 07-03-2012, 05:37 PM

By "coasting", I just meant that I lift my foot from the accelerator and coast when going down hills or when I have a stop sign or light ahead. By "accelerate slowly", I mean that I don't do jack-rabbit starts. I accelerate slower than most traffic around me, but not too slowly.

This tank was the first one during which I did not reset the AVG MPG gauge; however, I compute my mileage after every fill-up, and have only been getting about 31 or 32 MPG for all 8 or 9 tanks since I bought the car (new).

xcel · #6 07-03-2012, 06:00 PM

Hi Smile-n-Nod:

You also have the odometer offset to contend with. The OEM Trip A/B an Odometer under report actual miles by just over 3% in all of the Elantra's I have driven. You add that 3% back onto your actual mpg.

And like INATM mentioned, one tank, new driver, without all the tools and probably a more city than highway route with A/C a blasting spells for sub-EPA combined like numbers. I wish you lived near the Chicago area as we'd go out on a clinic this evening and you'd be punching out 50 + even with A/C and city traffic with the AT in short order.

It will take a while but hang out here and we'll make your wallet a lot heavier and the register at your favorite gas station a lot lighter if you care about such things. I know you do or you would not be here

Fire away with questions and we will do what we can to help.

Wayne

ALS · #7 07-03-2012, 06:01 PM

A couple of things you need to take into account is, it takes about five thousand miles for the drive train to break in and new tires are notorious for costing you a few mpgs for the first five to ten thousand miles. The other factors you need to figure in is your daily drive, it's length, hills, lights, stop signs, speed limits to mention a few variables. If your making short trips with low speed limits lots of lights and stop signs it will kill your fuel mileage.

RedylC94 · #8 07-03-2012, 06:48 PM

In addition to the variables ALS and xcel mentioned, some other factors that can make a big difference:
How fast are you going when traffic permits?
How do you deal with downhills when you don't have an unavoidable stop ahead?
Is that Elantra automatic or manual transmission?
Lots of idling, or not?
Do you start your coasting before stops early enough to avoid needlessly wasting much energy braking?
AC?

SD3_Driver · #9 07-04-2012, 08:16 PM

S-n-N don't get discourage by that, you're still new (3000 miles) and there are a lot of variables that you have not learned yet how to control certain things but it will come to you, don't worry... From my personal experience that thing is normal, lately my avg per the scan gauge and car FCD have been way off than the one I got after the top-off. From and avg of 59 (scan gauge) and 56(FCD) to an avg of 51 after the fillup. So I consider that normal, at least on the FFH.

joesgot4 · #10 07-04-2012, 11:08 PM

i have two 2012 hyunda accents one ive been driving for 11 months the other which ive had for one month and i learned how to get very good mpgs from the older one, but im just above the mpgs the car was rated for, i know how to drive for mpgs just im also struggling to figure my new accent out, the older 2012 came naturally getting great mpgs! If you have auto tranny how do you recomend getting up to speed?i