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Discussion Starter · #1 ·
A couple months ago, maybe January sometime, I started noticing I had to fill up sooner than usual. Before that time I could go a week + 1 or 2 days before filling up. Now I have to fill up within the same week - traveling exactly the same, my driving habits haven't changed (I'm heavy footed sometimes). I did get new tires in January and thought maybe it was because they obviously have more rubber than what came off that maybe the resistance was a little higher? I also considered the change to winter blend but wouldn't they change that over in November/December and not January?
I was getting approx. 23-25 mpg give or take before, now if I can get it up to 20 (driving like granny) it's a miracle. Averaging around 18ish. When I fill up my gauge says 323 til fill up (yes, I know this is an estimate), it has always been right in that ballpark before and after the change. But, before, the 323 was pretty accurate. Now, it starts at 323 and drops super quick thru the week and by Friday I'm at 50-75 "miles left". I don't even drive 250 miles per week. I can understand a little drop in winter and even after new tires but this seems like a lot when I haven't changed anything (but tires). We've tried a new air filter hoping to gain something to no avail. Is there anything else I should be looking at? I really don't want to take it into the dealership unless I have an idea that there is something going on....only because (as I read often on here) the dealership will come back with "can't replicate the issue" or something similar. It's happened to me before and I don't have enough time in the day to fiddle around, I like to try and figure out the issue myself so I'm prepared when I bring it in.
So, anyone else have a similar issue? Should I be cleaning something on the engine or running high test for a bit to "clean it out"? Just throwing things out there as I'm clueless!!! Thanks in advance!
 

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May need to take it out to the high way for a long drive to clear it up a bit. Double check the tire pressure too. My wife's tires set at 33 psi. Her car can get 442 when filled up. 70% free way and the rest in city. Also check for the camber setting of the rear tires and the brake slide pin lubrication.
 

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Sorry I can't lend any info on a solution but I recommend charting fuel usage with an app like Fuelly to keep an eye on things over time. We run different formulations here because of air pollution so mileage can vary, plus half the year my AC is on all the time, so I get seasonal dips in fuel economy. I also have a 2015 SFS. Honestly my only two complaints with this vehicle are I wish it had better sound deadening and that the mileage is disappointing. Steering response isn't great but I don't drive this vehicle in a way that that's all that noticeable. I rented a new Equinox in February that I think had the 1.5L turbo - it was only slightly less punchy but got great mileage and was quiet. I see the 2019 gets an 8 speed transmission, I'd think that would have to greatly help fuel economy - my Q5 which also had a 2.0L turbo got at least 1mpg better fuel economy than my SFS, albeit on premium.
 

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Discussion Starter · #4 ·
My tires are at 34 psi (I think, not where I can check at the moment), think I should lower them? Wouldn't that make it even worse? Holy crap how can you get 442 on a tank? I thought I was doing good at 323! Now I'm down to under 300. My commute is probably 60% highway, 15% city and 25% rural roads. When I got the new tires in January they did an alignment, actually I'm pretty sure the guy mentioned that the rear was far worse than the front - wondering if they screwed up the settings. I'll pass along the brake slide pin to my husband - he will probably know what that is/means - I don't. :)
I am also going to start charting my fuel usage so thanks mwl001 for the app, didn't know about it. I have to agree about the sound - the first year or so it was fantastic but over time it's gotten pretty loud. I had a 2009 as well and that was a major complaint of mine, thinking when it's time for a new vehicle we'll try a different manufacturer this time. The absolute best thing about this one is it's punchiness, ha ha but I try not to let it get out of hand very often, especially since this drop in mpg's started happening. But have to say it's pretty fun to whiz by someone and see the look on their face once in awhile! :)
 

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If you've not checked the tire psi since the new tires were installed - you might be surprised as in general you have to add air with new tires. psi checked at cold, and what is the max pressure for the tire - some are as high as 51, I'd suggest going to 35 psi or even 36, depends how harsh a ride you can tolerate.

Some tires yield significantly better mpg with a few extra psi. Also check tires for any early signs of uneven wear - this would indicate improper alignment.
 
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Discussion Starter · #6 ·
I check the psi once a week, they've not changed since being put on. I'll check again today. I think (by googling quick) the max psi is 44 but I've always read, and I could be wrong, that you're supposed to stay close to whatever is on the sticker inside the door. My husband just had the wheels off a week ago to scrape all the road sand out of them (upstate ny sucks) and they all looked good. And, no, the removal of the sludge didn't make a difference in mpg - had high hopes but nadda.
 

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for starters I would run a larger bottle of Techron fuel system cleaner through it. I just did that to my SF Sport and am getting about 1.5 mpg more.
 

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I check the psi once a week, they've not changed since being put on. I'll check again today. I think (by googling quick) the max psi is 44 but I've always read, and I could be wrong, that you're supposed to stay close to whatever is on the sticker inside the door. My husband just had the wheels off a week ago to scrape all the road sand out of them (upstate ny sucks) and they all looked good. And, no, the removal of the sludge didn't make a difference in mpg - had high hopes but nadda.
i've taken to running 37/36 f/r , ride is a bit harsh on rougher roads. Running too much pressure (40 psi +) can negatively impact handling. I've been less than impressed with the fuel economy overall but it takes a noticeable dip in winter with colder temps and winter blended fuel. If you've had colder than typical temps that will contribute to reducing the mpgs some , the friction bearing components in the Hyundai powertrain are a long way from state of the art, reliable yes, lightweight and low friction - not.
 

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Discussion Starter · #10 ·
i've taken to running 37/36 f/r , ride is a bit harsh on rougher roads. Running too much pressure (40 psi +) can negatively impact handling. I've been less than impressed with the fuel economy overall but it takes a noticeable dip in winter with colder temps and winter blended fuel. If you've had colder than typical temps that will contribute to reducing the mpgs some , the friction bearing components in the Hyundai powertrain are a long way from state of the art, reliable yes, lightweight and low friction - not.
Maybe we'll try raising them a smidge and see what happens. A couple stretches of road I'm on daily are pretty rough already (winter doesn't help) so don't want too rough of a ride. Hoping they switch over to summer blend soon so I can see if it makes a difference. But, I've had the car since '15 and never experienced such a harsh change in mpg. Could it be the tires themselves? I know there is mixed "reviews" on whether tires can actually cause a change but seems like everything happened all around the same time. IDK, at a loss......
 

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Maybe we'll try raising them a smidge and see what happens. A couple stretches of road I'm on daily are pretty rough already (winter doesn't help) so don't want too rough of a ride. Hoping they switch over to summer blend soon so I can see if it makes a difference. But, I've had the car since '15 and never experienced such a harsh change in mpg. Could it be the tires themselves? I know there is mixed "reviews" on whether tires can actually cause a change but seems like everything happened all around the same time. IDK, at a loss......
Well definately big differences in tires - the major mfg all produce tires that use special compounds to reduce rolling resistance and raise mpgs, you could be experiencing something from the tires along with something else - eg alignment issue, injector issue as a poster suggested using techron or you might run a few tankfuls of premium back to back to see if this improves the mpgs, if so it could point to something like a carbon buildup in the engine.

A lot of people will advise , myself included not to buy cheap tires - it's often false economy.
 

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Discussion Starter · #12 ·
I bought Firestone All Seasons, I've seen mixed reviews and not many as they are a new tire. Definitely better traction than what was on there but otherwise don't feel much of a difference. I'm going to by the techron on the way home and use it on my next fill up. Think I will try some premium for a couple tanks too. I've read about how to test injectors, etc. but that's out of my league...will have to talk the hubby into checking them out.
 

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You are very aware of the gasoline you buy. You hope it is the winter blended gasoline causes you the trouble. ( Not likely that big a difference ). Also you got the problem since new all season tires purchased. Why would you buy all season tires in winter? Make sure parking brake is not partial engaged. Have a spirited driving style sure does not help your fuel economy. How is the OCI ?
 

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Discussion Starter · #15 ·
Premier's were on my radar but out of price range (of course in hindsight would have saved more money buying them due to gas costs now). Why wouldn't someone buy all season tires in the winter? Most people put all season's on their car, I have no need for any other kind of tire. My driving style has been the same since I was 16, I certainly understand that can cause a difference in fuel economy but when driving the same for years and then mpg changing a couple months ago, I don't think that is the cause right now. CHecked parking brake a-ok....don't know what OCI is?
I filled up a little while ago as the display told me I had about 80 miles left to empty. It would only take 12.25 gallons...I had gone 216 miles since last fill up so I'm only getting around 17.6 miles per gallon. That seems so low to me when I was getting 22 or 23 a few months back. We even hooked up our code reader to it in hopes maybe something was throwing a code but nothing. I really don't feel tires could throw it off that much. I guess the next step is trying the fuel system cleaner and springing for some premium fuel - and of course the prices are going up right now, can't win, ha ha.
 

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OK, will throw this small possibility out there... the new tires are a different size/diameter and the miles driven is not the same as before (or the original tires were not standard size and new ones are). Curious what the Techron will do for you.
 

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Discussion Starter · #17 ·
OK, will throw this small possibility out there... the new tires are a different size/diameter and the miles driven is not the same as before (or the original tires were not standard size and new ones are). Curious what the Techron will do for you.
Nope, they're the same size. :( Have the Techron, will use it on next fill up.
 

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As DTech and others have mentioned.....New tires may offer more or less fuel economy by design. The cold weather will also lower fuel mileage, and that can be substantial if you do a lot of city driving (Believe you said you did about 50% highway) or you do a lot of restarts after it cools down.

Mileage usually comes down to tires, tire pressure being correct, and driving habits. Your vehicle can actually tell if it is running too rich. We frequently see customers who wish for us to check their vehicle because their mileage is lower than expected. If there is no servcie engine light on then there is nothing that can be done to change the fuel mileage.
 
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Discussion Starter · #19 ·
As DTech and others have mentioned.....New tires may offer more or less fuel economy by design. The cold weather will also lower fuel mileage, and that can be substantial if you do a lot of city driving (Believe you said you did about 50% highway) or you do a lot of restarts after it cools down.

Mileage usually comes down to tires, tire pressure being correct, and driving habits. Your vehicle can actually tell if it is running too rich. We frequently see customers who wish for us to check their vehicle because their mileage is lower than expected. If there is no servcie engine light on then there is nothing that can be done to change the fuel mileage.

Yep, I totally get it - frustrating for both sides. I'm still perplexed why it would be a good 5 mpg loss when it's never, ever happened before on this vehicle and thinking back to my last 2 Santa Fe's it never happened with a tire change either. My husband's pick up is getting almost the same gas mileage, it's ridiculous. Really hoping the Techron helps a little.
 

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My husband's pick up is getting almost the same gas mileage, it's ridiculous. Really hoping the Techron helps a little.
A lot and I mean many many heavier vehicles - some in excess of 800 lbs heavier produce superior gas mileage to the Sante Fe, so to me not ridiculous but indicative of the one of reasons the vehicle can be acquired in the words often used on here "for thousands less than comparably equipped competing vehicles" Fortunately gas prices remain relatively cheap or many buyers would be taking a closer look at that lower purchase cost vs fuel consumed over the yrs.

The new 8 speed transmission may help some with refreshed Sante Fe - reportedly lighter and using friction efficient components that competitors have utilized for years.

Techron worth a try, yrs back injectors were more prone to becoming sticky but modern ones generally don't have that issue.
 
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