Can't get past 20 MPG!

[JDC]

The last several highway only trips, on cruise at 70, for a total distance of 180 miles round trip, I can not get past 20 MPG. I've had three trips now all the same highway and destination. The first trip was 26 MPG.

I've changed my air filter, and will see if that helps next week. Any other ideas?

 

[Disaster]

Please explain further. You had three trips? The first was 26mpg? The next two were under 20mpg? Were they the same trip? How are you measuring gas mileage? How full or empty was the tank when you filled up?

 

[STREETS]

Very Strange as highway should be well into the 20's- 24-26.
I assume you are not driving in reverse and tires are inflated...lol

 

[ImInPA]

The last several highway only trips, on cruise at 70, for a total distance of 180 miles round trip, I can not get past 20 MPG. I've had three trips now all the same highway and destination. The first trip was 26 MPG.

I've changed my air filter, and will see if that helps next week. Any other ideas?

Other than a gas leak or a chinge in your driving habbits, your mileage seems to be very different than other members have posted. Airconditioning use now that it is getting wramer could have an impact. I strongly suspect that your right foot has discovered the pleasure of the Tau.

 

[ctrcbob]

You either have something wrong, or are doing something wrong (which I doubt).

I've taken three long highway trips, and on each, averaged between 27 and 29. (Have to look at my records to see exact milage).

Next week, will be taking another long trip and I'm sure my milage will be the same.
Around Lake County Florida, I average between 17 and 21, day in and day out.

 

[ASHDUMP]

Make sure your MPG gets reset after you fill up.... It should do it automatically but just double check.... and also, if you not sure, you can reset it yourself.

 

[Paulroger]

As a double check, you should also calculate your mileage manually. I maintain a spreadsheet and update with every fillup. To be consistent, I also try and fill up at the same station and pump and stop filling after the auto shutoff.

 

[nearwater]

To be 100% accurate, you have to calculate the MPG by dividing the miles you driven by the gallons of fuel you filled it with.
I use a free iPhone app that does this for me, and my mileage has been consistently 18MPG or a little higher. And this is 95% city driving.
You weren't looking at the mileage info on the cluster display did you?
If you were, it's very inaccurate and you should try calculating on your own.

Dan

 

[Bear]

May I suggest you look at this site for V8 MPG. Wish I was 20. http://www.fuelly.com/car/hyundai/genesis/gas v8

 

[Aquineas]

I took a long trip from Austin to New Orleans last week, and got about 25 on the way there, but I had a magical fill-up on the way back at a Shell station and averaged 28.2 on the way back! I haven't been able to get anywhere close to the latter number prior or since.

My typical during the week with about 80 percent highway and 20 percent stop and go is about 21.5 or so

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[Disaster]

I took a long trip from Austin to New Orleans last week, and got about 25 on the way there, but I had a magical fill-up on the way back at a Shell station and averaged 28.2 on the way back! I haven't been able to get anywhere close to the latter number prior or since.

Depending on pump fill differences, you might get up to a gallon fill difference from fill to fill. On an empty tank that is only a 5% error (1 mpg), but on a third tank it could be up to a 15% error (3 mpg.)

You'd have to have some pretty egregious filling deviation to amount to a 6 mpg error, like the original poster is seeing (though that isn't in the realm of impossibility because some people have had filling issues with their Genesis's.)

My typical during the week with about 80 percent highway and 20 percent stop and go is about 21.5 or so

That matches pretty closely to what my wife gets with her V6. She has a 15 minute drive to work, a couple minutes to highway, 11-12 minutes on the highway and then a couple minutes to her office. She averages 22-23mpg. Most of the gas is probably used in the first 5 minutes as the engine and catalytic converters are warmed up. It is about 1.5 mpg better than she got with her Volvo XC70 wagon, which had less power (230 hp) but was 4WD. The highway difference is bigger. We never got over 24 mpg with the Volvo on any trip (4 mpg difference.) The tank is bigger on the Genesis too, so we don't have to fill as often.

 

[SterlingDave]

The last several highway only trips, on cruise at 70, for a total distance of 180 miles round trip, I can not get past 20 MPG. I've had three trips now all the same highway and destination. The first trip was 26 MPG.

I've changed my air filter, and will see if that helps next week. Any other ideas?

I'm as amazed as several others who have responded to your issue.

We just came back to Denver from Phoenix on Monday in our Gennie and here's our MPG:

After filling up in Heber, AZ, we drove to Holbrook, AZ, a distance of 44 miles. I drove on cruise set at 65 on a two lane highway that was generally straight with little rolling terrain. When we got to Holbrook the car showed an amazing 37.2 mpg. Then we got on I-40, drove through to Albuquerque, NM, before stopping and filling up. I then calculated our mileage to be 32.1 MPG while driving at a cruise control setting of 75 MPH.

Then we drove non-stop (except for a nature call and driver swap) into Denver. I filled up again and manually calculated our mileage to be 29.8 mpg. This was while driving at a cruise setting of 75 mph on I-25 (except while my wife was driving with cruise set "slightly" higher at 80 for about half the distance).

I cannot believe that our mileage is that atypical for this car. But yours? Unless there is something wrong with your calculations, or you've developed leadfootitis (ha, ha) you must have something wrong with your car that begs service. If your are certain of your calculations....take it in for test (under warranty). No way should your car be getting that horrible mileage!

Good luck.

 

[ASHDUMP]

May I suggest you look at this site for V8 MPG. Wish I was 20. http://www.fuelly.com/car/hyundai/genesis/gas v8

I'm on that list. Seems like I'm ahead of the gang here....

 

[kev4]

You can not trust that MPG estimater, it is just a ball park indicator. You need to do a trip (200miles)starting with a full tank of gas, once the trip is done you need to fill the tank once again, then from the gas pump copy the amount of fuel you used and how many mile you went and you will then come up with an accurate MPG. ie 9 Gallons of fuel / 200 miles = 22.2mpg 8.5 gallons / 200miles= 23.5 etc.....

 

[JDC]

I'm as amazed as several others who have responded to your issue.

I cannot believe that our mileage is that atypical for this car. But yours? Unless there is something wrong with your calculations, or you've developed leadfootitis (ha, ha) you must have something wrong with your car that begs service. If your are certain of your calculations....take it in for test (under warranty). No way should your car be getting that horrible mileage!

Good luck.

Yes, the calculations are correct. Since this is only three trips calculated, first being 26.x... and the calc's are correct. I will wait for another with reasonable winds as I am thinking that the last two trips had 30-70 head winds on the returns. That's probably the culprit. No lead foot.

This car almost drives itself.

Your 30's + MPG - is with the 8 cyl?

 

[Lowblow]

After filling up in Heber, AZ, we drove to Holbrook, AZ, a distance of 44 miles. I drove on cruise set at 65 on a two lane highway that was generally straight with little rolling terrain. When we got to Holbrook the car showed an amazing 37.2 mpg. Then we got on I-40, drove through to Albuquerque, NM, before stopping and filling up. I then calculated our mileage to be 32.1 MPG while driving at a cruise control setting of 75 MPH.

I also drive a 4.6 Tech and have yet to fall below the advertised MPG ratings.

Mixed commute (90% city): 19.5-21.5mpg
Road Trips (100% Highway): 27-32mpg

I am an "Eco" driver. I typically drive quite slow and use neutral on all downhill runs. During my daily commute I rarely go past 45mph so my results may be atypical.

BTW: I find the radar guided cruise really maximizes fuel consumption on long trips. It also reduces fatigue because that car almost drives itself.

 

[waltbald]

...

BTW: I find the radar guided cruise really maximizes fuel consumption on long trips. It also reduces fatigue because that car almost drives itself.

Something doesn't sound right. If you consume the maximum amount of fuel, that would be a bad thing, but it sounds like you're saying it's a good thing.

So, does the radar guided bit burn more gas or less?

many thanks,

 

[SterlingDave]

Yes, the calculations are correct. Since this is only three trips calculated, first being 26.x... and the calc's are correct. I will wait for another with reasonable winds as I am thinking that the last two trips had 30-70 head winds on the returns. That's probably the culprit. No lead foot.

This car almost drives itself.

Your 30's + MPG - is with the 8 cyl?

V8? You bet it is! This car has been a pure delight. If my mileage gets much better, I may have to stop every once in a while to drain out the extra gas!

And before any of you guys ask...NO, she's not for sale.

 

[Lowblow]

Something doesn't sound right. If you consume the maximum amount of fuel, that would be a bad thing, but it sounds like you're saying it's a good thing.

So, does the radar guided bit burn more gas or less?

many thanks,

haha. Whoops. I meant that the feature is better at saving gas than my foot. I just love that this car has multiple personalities. When I want it to be economical, it can be. When I want it to hit warp speed, it does so in an instant.

 

[Rey]

Your drop in gas mileage may be mechanically caused. Do check your air filter to make sure it is not obstructed. It is unlikely that obstructions can get into the airbox, but it is so easy to check.
Another place to check is brake caliper drag. Usually, brake drag will be in just one caliper; and if this is so your car will pull to the direction where the caliper is located. However, brake drag can be very subtle. Many times it can be noted by temperature differentials between calipers. The best way to measure temperature differential is with a non-contact infared thermometer, but sometimes just your hand close to the caliper can feel a difference.
A more rare source of bad gas mileage in a new car is a plugged exhaust. It is not unheard of for a cat converter to mechanically fail, but they usually rattle when they do.