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2009-2010 Hyundai Sonata



  • I have a 2009 Sonata GLS Auto 4 cyl. The car lurches forward with only minimal accelerator pressure. I don't really mind, but I think this may adversely impact my gas mileage as I am getting only 23 MPG with mostly highway driving. Does anyone notice this issue? I am wondering if dealer maintenance can correct this problem under warranty?
  • stephen987stephen987 Posts: 1,994
    edited December 2010
    My guess is that it's not a mechanical problem--the car is functioning as designed. Frequently cars are set up to appear more powerful/responsive than they really are, through the design of the throttle system.
  • backybacky Twin CitiesPosts: 18,681
    But 23 mpg on the highway is not acting as designed, under "normal" highway driving. Hyundaisonata, can you tell us about your highway driving? What speed? How long is the typical trip? What kind of weather? How many stops? How's traffic? Are tires inflated to spec? Does your gas have ethanol?

    One way to check if the car is getting the fuel economy it should is to find a flat stretch of open highway with little traffic, so you can maintain a steady speed. This drive should be several miles. Then warm up the engine and as you start cruising at a fixed speed, reset the mpg meter. Keep the speed at the limit, and try to use a light foot on the pedal (or use cruise control). Be sure you are in 5th gear. If the speed limit is 55-60, you should easily hit the EPA highway rating for the car--actually you should exceed it. At 65-70, you should still be able to hit the EPA rating. Above 70, you should still get WELL over the 23 mpg you are getting now.

    If you don't get results like that on this test, and the tire pressures are correct and weather is not real cold, I'd say there's something that needs to be checked by the dealer.
  • I bought a used 2009 Sonata GLS with 21k on it. Nice car but I notice wind noice, almost a whistle-like sound on the highway. Had a S-series Saturn 10 years ago that did the same thing. I was told it was air passing around the side view mirrors, don't know what the cause on the Sonata is.
  • thegraduatethegraduate Posts: 9,731
    Change your air flow from fresh to recirculate and let me know if it improves.
  • carbuyer109carbuyer109 Posts: 9
    edited January 2011
    No change when the air is recirculating vs. open, it does seem to be coming from the side view mirrors though. Wish there was some way to get rid of it. What I find strange is that I did not come across this issue anywhere. I researched this car on Edmunds, Car and Driver, Motortrend, Consumer Reports etc. Never came across this issue, googled it after I noticed it on my car and came across it on this forum. Thanks for the suggestion though!
  • thegraduatethegraduate Posts: 9,731
    Well, I was hopeful. I have a whistle at higher speed (60+) that improves if you set the ventilation to recirculate. I think it has something to do with a leaking sunroof and airflow pulled through it. My weatherstripping doesn't appear to meet in the middle.
  • backybacky Twin CitiesPosts: 18,681
    edited January 2011
    I have a 2007 Sonata, same mirrors as yours, no whistle that I have noticed. However, different people can be sensitive to different sounds. Very little wind noise at all in fact unless I drive into a strong headwind, as I did on a long trip a couple of weeks ago, then there was some general wind noise at 70 mph cruise. Do you drive in strong winds, or do you hear the whistle even on a calm day? At what speed do you start hearing the whistle? (I do not have a moonroof, fwiw.)

    The interesting thing about the whistle is I remember distinctly that one of the justifications HMA made for the 2006-10 USA-spec Sonata not having folding mirrors was to reduce wind noise. I always suspected that was balderdash, and real reason was that fixed mirrors are less expensive.
  • ay50ay50 Posts: 11
    I have a 2009 SE with the Kuhmo 17" tires. I'm not sure if we're talking about the same type sound but I have noticed that on a certain type of highway road surface here in Texas I hear a high-pitched whine or whistle. Upon switching to a different type of highway surface it goes away.

    I don't remember what type of surface it is that I hear it on but the OP might take this into consideration.
  • crkyolfrtcrkyolfrt Posts: 2,345
    Have you had a windshield replaced lately? Check all the trim around the edge to ensure the OEM moulding is complete and with nothing missing or not attached properly right out to the edge in places. This was the cause of an elusive whistle on an X Trail I had. Doesn't take much. Also confirm the wipers have been reattached on their stems so that they rest at the correct position. Those too can cause noise. I feel your pain though, I really don't like wind and road noise. That and poor seats and inadequate HVAC are among my biggest beefs with a car. Many cars will have some noise at 60 to 65+. But if you have whistling at 50 mph, that should be able to be found. Also look for previous mirror damage and gap discrepancy from one side to the next. If one side is wider, try using black tape to close the gap and test again. If you want to try to rule out your driver's door. Tape the entire door up tight, then crawl in from the passenger side. Try it, next, then tape all around the perimeter of where the glass meets the moulding, and test again. Start simple and work your way up to more effort as needed. Speaking of simple...have you confirmed that all the windows are up, in back doors too? Any previous accidents on car?
  • backybacky Twin CitiesPosts: 18,681
    I hear a whine on certain concrete road surfaces also; my Sonata has Kumho Solus tires. But that whine sounds much different than a wind noise.
  • carbuyer109carbuyer109 Posts: 9
    edited January 2011
    I appreciate everyone's input, I will try to reply to everyone's comments so forgive me if this rambles a bit. The noise starts at 40mph and up, I do not have a moonroof, (basic GLS), I bought the car used, nothing about the windshield replaced on the Carfax report, doesn't look replaced, the tires are origional to the car (Michelins I think), doesn't only happen in strong winds, though this does make it worse. Maybe it is the seal around the door, I will have to look into that, maybe a bit of air is entering the cabin. Will check the wipers too (once this storm leaves New York :). Thanks again everyone.
  • carbuyer109carbuyer109 Posts: 9
    edited February 2011
    Finally got some warmer weather, found a few small gaps around the drivers side mirror and filled them with black silicone but did not help, do not see any other differences between the drivers and passengers side windows, doors, weather stripping or mirrors but the whistling is very bad, especially when it is windy. Not sure what else to do but take it to dealer. Thanks for everyones ideas.
  • retsabretsab Posts: 10
    I have an '09 Sonata GLS, haven't noticed any wind noise but I did notice my drivers side mirror weather covering (black triangle surrounding the mirror base) starting to come loose at the top. I am worried about snow and moisture getting behind, freezing and causing difficulty with the mirror. I took it to the dealership, they thought it might be the Weather Tec window shields causing this problem but decided to order a new mirror for my car. It has been so cold and the roads so messed up I would never notice wind noise here in Western New York.
  • That is what happened to my drivers mirror so I assumed the gaps were causing the noise, as someone else posted, it doesn't take much, I don't have window shields so I think the mirrors are just seperating. Did you have the dealer replace it or buy and replace yourself. I though about buying an OEM on the web (did this for a Saturn years ago and it was fine). Will cost about $70 this way, the dealer will charge about $300 I imagine including installation costs. It is a high pitched whistle though, not typical wind noise so air must be getting in or around something.
  • retsabretsab Posts: 10
    Dealer is going to replace it under warranty, has been ordered but not installed as of this date. I might have an advantage due to the fact that this car is a replacement for another in a Lemon Law decision 2 years earlier.
  • I see, I bought my car used, the mirror had a small crack in the bottom front corner where it mounts to the door (I did not notice this when I bought the car) so I was afraid the dealer would not replace it since this was damage rather than a part failure. This is why I decided to caulk the gap myself. Of course now I've tampered with it and I still is no better. Someone had suggested removing the mirror and covering the hole then taking the car for a drive. This way if the noise stops, I know its the mirror. Think I will try this when it warms up.
  • joel607joel607 Posts: 3
    Have an 09 Sonata with the same issue...creaking snapping noise coming from passenger's side dash area...interestingly enough the 2011 has the same issue and the fix is to loosen are reposition and tighten the hood mount. Since the hood mount area is almost underneath the windshield and dash area makes sense it would sound like it's coming from the dash...mine is worse when cold and gets better as it gets really hot but flexing the frame when hitting bumps makes it worse. Mine is at the dealership right now and have a good relationship with service manager and he knows i'm in the automotive diagnostic field, I passed on what I found out and will let you know how it turns out. My suspension thunking noise was 80% addressed with new strut and strut mount and making sure the strut fork was tight, the other issue is a balljoint that the boot is crushed and collapsed on one side that hopefully will take care of the rest of the suspension noise, otherwise I'm really happy with my 28 MPG average and the overall features and styling of the's a limited edition I purchased used with new warranty still in place.
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