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I went from Charlotte, NC, to just east of Pittsburgh last Friday, went to Niagara falls and back on Monday, drove all around my old stomping grounds visiting people, and drove home this morning. I managed to put just under 2000 miles on the car, and on the trip up and the trip back I only got 31mpg. I was going between 60 and 75 the whole time and it's up and down hills through virginia and northern NC, but i expected a bit more. I had about 40lb of luggage and of course my heavy wheels, should i have gotten better than 31?? or is that ok under the circumstances? your thoughts.....
 

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Up and down hills (HP required) and you got 31 and are unhappy? I have driven those hills, lots of accelerator up and none down.

Stock wheels? Any other changes?
 

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31 is a TON better than the 25 i got when i drove my santa fe up there. I just wasn't sure if i should be getting better than that. I coasted in neutral all the way down the 7 mile hill at Fancy Gap on I-77 also!
 

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QUOTE (Bearcats @ Aug 5 2010, 05:26 PM) index.php?act=findpost&pid=347396
Up and down hills (HP required) and you got 31 and are unhappy? I have driven those hills, lots of accelerator up and none down.

Stock wheels? Any other changes?
just aftermarket 20" wheels, nothing else. It was 31.8 to be exact so i guess that's almost 32
 

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My first fill-up was today. 444 miles around town except for the 60 mile trip back from the dealer.
Avg 27.56 mpg using std calculation. (although dash said 26.4) Not that this means anything, but between the hills and the speed (70 mph does suck the juice) I would think 31 was pretty good. You could have always got a Prius :)
 

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Long hills and city driving seem to eat away at the mpg. I found it is easy to do 40+ mpg on the interstate so long as mountains are not involved. I doubt the wheels were much of a factor unless you were doing start and stop driving. Also, must people will get better mileage with curse control on.
 

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QUOTE (jdubs @ Aug 5 2010, 07:01 PM) index.php?act=findpost&pid=347421
Long hills and city driving seem to eat away at the mpg. I found it is easy to do 40+ mpg on the interstate so long as mountains are not involved. I doubt the wheels were much of a factor unless you were doing start and stop driving. Also, must people will get better mileage with curse control on.



I wish I had the "curse control" option on my Hyundai. The [email protected]#% traffic and the stupid &%$#@ drivers get on my last nerve every time! I just can't help myself #$%&* and #^%#*.
 

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I would say for location and your wheels you did just fine. Was the 31 by computer or by hand math. Miles/Full Tank Gallons. **** idiots who cheat and say they get better by math then computer are full of ****. **** my last tank was 444 miles on it but when I filled up I only pumped 14 gallons!!! LOL BS I can make my MPG look like gold when I cheat.
 

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QUOTE (ssmuff @ Aug 6 2010, 11:54 AM) index.php?act=findpost&pid=347576
I would say for location and your wheels you did just fine. Was the 31 by computer or by hand math. Miles/Full Tank Gallons. **** idiots who cheat and say they get better by math then computer are full of ****. **** my last tank was 444 miles on it but when I filled up I only pumped 14 gallons!!! LOL BS I can make my MPG look like gold when I cheat.

Wow, why all the hate? Over MPG's? Now who is exactly "cheating" who, out of what?
You, need to use your
"curse controll" more often.
 

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lol man that aint crappy dude! 31 is pretty good imo. It is good considering your wheels and hills. hmmm "wheels and hills" could make a song about that.
 

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If your using cruise control going over hills an such you should through it in the slap shift mode. You will get better gas mileage as the car doesn't have to down shift and through it up to 2500+ RPMS. Thats at 65<<. Finished my tank up around 580+ miles with 34.1mpg+.Test it out. Hense the cpu told me I was getting 37+ lol
 

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QUOTE (rcweimer @ Aug 5 2010, 04:51 PM) index.php?act=findpost&pid=347406
just aftermarket 20" wheels, nothing else. It was 31.8 to be exact so i guess that's almost 32

That sounds great for hills and 20"'s. Plus I am sure you were running AC which probably steals a little.



Question? How are you doing your calculation? I am sure with the 20" wheels your odometer/speedometer is not 100% accurate anymore. How are you compensating for that ?
 

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QUOTE (rcweimer @ Aug 5 2010, 02:49 PM) index.php?act=findpost&pid=347405
31 is a TON better than the 25 i got when i drove my santa fe up there. I just wasn't sure if i should be getting better than that. I coasted in neutral all the way down the 7 mile hill at Fancy Gap on I-77 also!
Actually putting it neutral causes you to burn more fuel than leaving it in gear. If you're traveling over 25 mph and leave the car in gear when you take your foot off the accelerator, the car's computer will shut off the injectors burning NO fuel. The reason the engine doesn't stall is because the wheels are still turning in gear which keeps the motor running. When you put it in neutral, the engine goes to idle and the injectors have to run to keep the engine from stalling.

It sounds backwards I know, but it's true. Just a heads up.
 

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I would say it's the larger(heavier) wheels killing the fuel mileage. I have worked any many new car dealers with the same concern. I'd say 99% of the time the low fuel MPG is due to oversized wheels. It's just like adding a trunk full of speakers, more weight= less MPG.
 

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Discussion Starter #16
QUOTE (chitown1211 @ Aug 6 2010, 01:37 PM) index.php?act=findpost&pid=347609
That sounds great for hills and 20"'s. Plus I am sure you were running AC which probably steals a little.



Question? How are you doing your calculation? I am sure with the 20" wheels your odometer/speedometer is not 100% accurate anymore. How are you compensating for that ?
good point, i never thought of the overall hieght of the wheels playing a part. I'll have to look into that.
 

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QUOTE (lovemysantafe @ Aug 6 2010, 05:15 PM) index.php?act=findpost&pid=347650
Actually putting it neutral causes you to burn more fuel than leaving it in gear. If you're traveling over 25 mph and leave the car in gear when you take your foot off the accelerator, the car's computer will shut off the injectors burning NO fuel. The reason the engine doesn't stall is because the wheels are still turning in gear which keeps the motor running. When you put it in neutral, the engine goes to idle and the injectors have to run to keep the engine from stalling.

It sounds backwards I know, but it's true. Just a heads up.

this needs to be in the "i'm about to go on a hilly trip" manual
 

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A few thoughts:
In this now famous article,

http://www.caranddriver.com/features/10q1/...ested-tech_dept

the VW lost .8 mpg going from 18s to 19s. It seems safe to say that going to 20s on your car cost you at least one mpg. (Going up and down hills it could be worse.)

Chitown brought up an excellent point about tire size and mileage calculation. But that affects all of us. Most speedometers are off by about 3%. When the speedometer indicates 60 mph we're actually going only 58 mph. For most of us, that means our odometer is also off by the same 3%. Because it overstates the miles travelled by 3%, it artificially boosts the mileage by 3%. If we calculate 35 mpg (i.e. 450 miles/12.85 gallons), we really only got 34 mpg (436 "actual" miles/12.85 gallons). That means most of us get about 1 mpg less than we calculate.

How does this affect your 20 inch tires? I believe the recommended tire size for 20" wheels on a Sonata is 235/35-20. Is that what you run? If yes, they are 1.9% larger than the 18s. That means they will correct your car's speedometer by 2%. If your speedometer was off by the normal 3% before, your speedometer's error might be off 1% or less right now. That means the speed you read on your speedometer is probably close to dead-on accurate right now and the mileage you calculate is also probably very accurate.

When you consider your super heavy wheels (-1 mpg), hills (-1 to -2 mpg), A/C usage (-1 to -2 mpg), and "real" mileage (no artificial boost of 1 mpg), 31 mpg is not bad. You probably got the equivalent of 35-37 mpg on an ideal flat road.
 

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QUOTE (Blue07 @ Aug 7 2010, 01:08 PM) index.php?act=findpost&pid=347811
A few thoughts:
In this now famous article,

http://www.caranddriver.com/features/10q1/...ested-tech_dept

the VW lost .8 mpg going from 18s to 19s. It seems safe to say that going to 20s on your car cost you at least one mpg. (Going up and down hills it could be worse.)

Chitown brought up an excellent point about tire size and mileage calculation. But that affects all of us. Most speedometers are off by about 3%. When the speedometer indicates 60 mph we're actually going only 58 mph. For most of us, that means our odometer is also off by the same 3%. Because it overstates the miles travelled by 3%, it artificially boosts the mileage by 3%. If we calculate 35 mpg (i.e. 450 miles/12.85 gallons), we really only got 34 mpg (436 "actual" miles/12.85 gallons). That means most of us get about 1 mpg less than we calculate.

How does this affect your 20 inch tires? I believe the recommended tire size for 20" wheels on a Sonata is 235/35-20. Is that what you run? If yes, they are 1.9% larger than the 18s. That means they will correct your car's speedometer by 2%. If your speedometer was off by the normal 3% before, your speedometer's error might be off 1% or less right now. That means the speed you read on your speedometer is probably close to dead-on accurate right now and the mileage you calculate is also probably very accurate.

When you consider your super heavy wheels (-1 mpg), hills (-1 to -2 mpg), A/C usage (-1 to -2 mpg), and "real" mileage (no artificial boost of 1 mpg), 31 mpg is not bad. You probably got the equivalent of 35-37 mpg on an ideal flat road.
My tires are 225/35/20. Overall height on the stock 205/65/16 tires is 26.49....The overall height on my 225/35/20's is 26.20. They are actually shorter than stock tires. So the only thing that could be hurting me is the weight of the wheels.
 

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QUOTE (rcweimer @ Aug 10 2010, 05:04 PM) index.php?act=findpost&pid=348485
My tires are 225/35/20. Overall height on the stock 205/65/16 tires is 26.49....The overall height on my 225/35/20's is 26.20. They are actually shorter than stock tires. So the only thing that could be hurting me is the weight of the wheels.
You're right. The 225/35-20 tires are about a 1/10th inch shorter which translates to .4% smaller. (Sadly that means your tires did nothing to correct any speedometer error.) You know RC, I am positive your car is not as bad as that trip made it look. First, the A/C hurt your mileage. Second, the hills absolutely did too. The problem will hills is that they don't average out. You never "save" going down the hill what you "burned" going up the hill.

I know this sound's geeky, but I've done the mpg calculations many times. Here are some real numbers from my Scan gauge. Normally, my car gets 35 mpg on a flat road at 60 mph. However going up hills, it averages about 20 mpg. Going down hills, it averages about 90 mpg.

Suppose you're traveling on Rt. 81 and you hit a hill that is exactly one mile up and one mile down (road distance). With the cruise set at 60 mph, you would spend exactly one minute going up that hill, during which time you get only 20 mpg and then you would spend exactly one minute going down the hill, during which time you would get 90 mpg. What's your average mpg to cross that hill? One might think because you get 20 mpg for one minute and then 90 mpg for the other minute, you would average 55 mpg for those two minutes. It doesn't work that way. I'll spare you the calculations (unless you want them), but the average mpg for that hill would have been 32 mpg. Had those two miles been on a flat road, the car would have averaged 35 mpg.

Hills hurt mileage. A road tip across the Appalachian Mountains is simply the wrong time to test highway mileage. For that matter, anyone who lives in the mountains should never expect to get the same mileage as someone who lives in the plains. You can't change the laws of physics.
 
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