Accuracy of "Average Fuel Consumption"

[Mark_888]

Has anyone figured out how accurate the Average Fuel Consumption display is? I realize that it resets when the gas tank is filled.

 

[billygator]

I have never realized the mileage advertized on the screen. Seems to run about 10% higher than actual. For the record, I average about 17 when doing only City driving, and about 25 on the couple of tanks that were exclusively highway. Since that is what is advertised, I am fine with it, but my other cars (Toyotas, VW's) were very accurate on these readings.

 

[JOwest]

I drive mostly short distance and in the city. My average fuel consumption reading is about 15% lower than actual.
I guess if you drive 50% city and 50% highway then the "average" reading maybe closer to actual.

 

[scottdk]

I have noticed after refueling and using basic math to configure the mpg, that the computer seems to show about 1mpg more than I actually get.

 

[Nabber]

Might be interesting to calculate this taking into account your speedometer inaccuracy as well. If a speedometer reads 5% fast, it may use that number as the miles travels in the calculation. I am not sure if the speedo and odo are linked like older cars that use a cable/gear system.

 

[dtreter]

I don't know the inaccuracy of the readings but I am very happy with my results. Whether it is 1 mpg less or 5% less, I got a great value. I traveled the PA turnpike from Pittsburgh to Philadelphia, a 300 mile trip over the Allegheny mountains, and got 29.2 mpg at 78-82 mph (yes, I know I was speeding). I am very impressed with the mpg obtained. I will try to calculate exactly the mph on the return trip to compare to the car's computer.

 

[Mark_888]

I don't know the inaccuracy of the readings but I am very happy with my results. Whether it is 1 mpg less or 5% less, I got a great value. I traveled the PA turnpike from Pittsburgh to Philadelphia, a 300 mile trip over the Allegheny mountains, and got 29.2 mpg at 78-82 mph (yes, I know I was speeding). I am very impressed with the mpg obtained. I will try to calculate exactly the mph on the return trip to compare to the car's computer.

Is that the V6 or V8?

 

[silverado]

my mpg computation is spot on.

 

[ImInPA]

Every vehicle I have ever owned with the Trip computer has always been somewhat optimistic in its fuel consumption reading. They always report better avg. mpg that is somewhat better than I actually calculate out at the pump. Still a great feature to have in a car.

 

[ctrcbob]

Last time I did the math, the true reading was 0.5 mpg lower than the display. Not enough to bother doing the math every time. Perhaps I do the math once a month.

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[dtreter]

Is that the V6 or V8?

V6 with tech package and about 2200 miles on the odometer so the engine is just partially broken in. There was no local (start and stop) driving...just pure interstate roads. I wasn't expecting those numbers. I am hoping to get the same numbers on the return trip tomorrow.

 

[moose66]

From Pitt to Philly . . . . hmmm . . . . .mostly downhill/flat maybe? With little or nor uphill climbs. That is awfully high. Especially when you factor in your reported speed. That's great mileage, however attained!

 

[dtreter]

From Pitt to Philly . . . . hmmm . . . . .mostly downhill/flat maybe? With little or nor uphill climbs. That is awfully high. Especially when you factor in your reported speed. That's great mileage, however attained!

Pittsburgh is moderately hilly area, Philadelphia is mostly flat but in between are the Allegheny mountains. It is a good test for this car and it had very surprising results. Elevation near my house (Pittsburgh) is 700 ft, destination near Philly is about 500 ft.above sea level. Mountains are about 3000 ft. Two thirds of the drive is through mountainous area.

I know this seems impossible at my speed but this is what my car showed.

Trip 300 miles
Drive time 4 hours 20 minutes
Two bathroom stops
speed control set at 78 most of the way

 

[moose66]

dtreter . . . not questioning your numbers at all. Just thinking out loud at how you could have gotten such good gas mileage. Hopefully you can always get that mileage! Good info by the way on the elevation differences from Pitt to Philly. Enjoy your ride!

 

[dtreter]

Return trip from Philly to Pittsburgh got 27.1 mpg. Same approximate speed (maybe 2 mph slower) and distance. Average mpg 28.15 round trip. I am very happy with mpg.

 

[Mark_888]

I have the V6 and recently got 27.5 mpg average on a recent 40 mile trip on Atlanta freeways from 4-5 PM, and there were a few times when traffic was slow (almost dead stop once or twice), and I had to stop at a toll booth. I think I could get at least a 28.5 mpg reading at a steady speed of about 70-75 mph with no traffic congestion. I say "reading" because I don't know how accurate the display really is.

One thing I noticed is that I don't get as good of mileage at a steady 50 mph as I do at 70 mph. This is different than any other car I have driven. I think that is because of the very tall 6th gear on the V6 tranny.

Another thing I noticed is the V6 tranny coasts better than any automatic transmission I have ever driven, almost like a manual in neutral. But it down-shifts nicely when the brakes are applied to help slow the vehicle.

I think the V6 engine and transmission are near perfect for my needs. Hopefully they will be reliable also.

 

[moose66]

Looks like you guys with the V6 are doing quite well in the MPG area on extended trip. I haven't done any decent long trips to gauge how well (or poorly) the V8 will do. I'll chime back in when I can get a trip or two in.

 

[wild willy]

Very interested in this car, and am reading as much as I can about it before I make a decision. My experience with trip MPG accuracy has been as follows. I have a 3.5 L Altima that gets about 2-3 mpg less than the trip comp. says in mixed driving conditons. If I hop on the highway, I will get 30 and it will be spot on.

I had an 04 GTO with an LS1 V8. The trip computer on that was spot on under any conditions. For the record, that V8 would get 30MPG with a fully loaded trunk, fully loaded back seat and me and my father up front heading to the OBX. Speeds varied from 55-95.

Kinda makes you wonder what these little motors do so poorly in comparison. Not to mention the GTO weighed in at 3800lbs.

 

[SCVDon]

We have a V8 and my wife drives 45 miles each way to and from the SCV to the LAX area (most if it on the 405) and we are pleased with getting about 20 - 21 mpg in LA's horrible traffic at rush hour. Car is now at about 1100 miles and so could improve in the next few thousand miles as break-in continues. On a recent cruise-control 65 mph leg from the SCV to Fillmore we got in the 28.5 - 29 mpg more-or-less based upon the car's data. Guess that is very decent for this car.

 

[SCVDon]

Very interested in this car, and am reading as much as I can about it before I make a decision. My experience with trip MPG accuracy has been as follows. I have a 3.5 L Altima that gets about 2-3 mpg less than the trip comp. says in mixed driving conditons. If I hop on the highway, I will get 30 and it will be spot on.

I had an 04 GTO with an LS1 V8. The trip computer on that was spot on under any conditions. For the record, that V8 would get 30MPG with a fully loaded trunk, fully loaded back seat and me and my father up front heading to the OBX. Speeds varied from 55-95.

Kinda makes you wonder what these little motors do so poorly in comparison. Not to mention the GTO weighed in at 3800lbs.

I also have a GTO and remember you from that forum. You were never too happy with the GTO, if I remember correctly.