08 Sonata - Getting 15 MPG!?!?

jordanlevin8jordanlevin8 Member Posts: 4
Hi. I recently bought a CPO 2008 Hyundai Sonata GLS (4 cly).

The car is getting 15MPG! I dont know what to do. I took it to a dealership and they tried to screw me out of $400+ for a "spark plug, fuel injection, and air filter cleaning."

They did a full inspection and told me that nothing major was wrong. No leaks etc...

What is the problem? I live in LA and obviously am stuck in traffic alot... But how is my car getting such terrible mileage? I drive with the lightest foot ever.

If i change my spark plugs and put in fuel injection cleaner in my gas tank, will this really make a difference?

Please help!


  • yul711yul711 Member Posts: 8
    After I replaced spark plugs at 100K miles in my 2006 Sonata with iridium plugs, my gas mileage improved by more than 2 mpg. I would also suggest to replace air filter if it's dirty/clogged, it is very easy and inexpensive.
  • jordanlevin8jordanlevin8 Member Posts: 4
    2MPG would be nice. But i would realistically like to get the 25 that I thought I was getting... And I'm only at 60k miles!

  • yul711yul711 Member Posts: 8
    I use regular gas and get around 26 mpg on average with around 30% city (usually heavy traffic), 70% highway (2600 - 3000rpm) driving. In my experience, getting under 20 mpg in the city or heavy long highway traffic is not unusual.
  • jordanlevin8jordanlevin8 Member Posts: 4
    I barely get 20 MPG highway... I reset my MPG counter on the highway and was getting literally 20-21... Something is clearly wrong im getting barely 15...
  • backybacky Twin CitiesMember Posts: 18,946
    Have you tried this: get out of LA, find an open stretch of relatively flat highway that you can set the cruise control on, reset the mpg meter, then set cruise at the speed limit and drive at least 10 miles. Then turn around and go back the same way. Make sure your tires are inflated to spec, car is maintained as suggested (at 60k it's due for a major servicing that would include plugs, oil, and air filter) before the test.

    If you don't see at least 30 mpg in this test, I'd wonder if there's something wrong with the car. If you see 30+ mpg, then it's your LA commuting that is killing your mpg. BTW, the EPA combined rating for the 2008 I4 AT is only 24 mpg, and 21 city. And that is not in LA traffic.
  • lightfootfllightfootfl Member Posts: 442
    edited October 2011
    It might not apply to you, but my 2006 V-6 LX Sonata, with right at 30,000 miles recently finished a trip of about 1400miles and my overall mileage was not everything I would have liked either, but it wasn't bad, please take a few minutes to read my #759 on Sonata Real MPG to see how I did. Just another two cents worth. It shows my overall mpg for the trip.
  • yul711yul711 Member Posts: 8
    I am not an automobile pro, just want to mention a few point to consider. May be your brake pads are "sticking" to brake rotors, causing extra friction when driving? You can check this by touching wheel hub during/after stop, it could be hot from constant friction. Do you feel that your car does not have adequate power on highway? One of the engine cylinders may be not working properly wasting gas? This could be come from defective spark plug, cylinder coil, coil wire, ignition system malfunction, vehicle computer malfunction, bad oxygen sensor (just a few that come to mind). To begin with, I'd suggest to replace spark plugs and show them to good mechanic, he may tell you if there are obvious problem inside the cylinder. Ask your mechanic to check ignition wires for good electric signal connectivity to coil and look and the coils. May be you can find a good local mechanic that could do a good job much cheaper that a dealer? Just my 2 cents.
  • targettuningtargettuning Member Posts: 1,371
    If any of those "engine malfunction" items you suggested had actually occurred the CEL (check engine light) would be ablaze. If even one cylinder misfires momentarily for any reason it will trigger a code and a resulting CEL...I know it just happened to me when cylinder #4 spark plug failed on our Saturn. This thing, the OBDII diagnostic tool has so many sensors and can detect so many faults, even brief ones, it is scary so I believe the problem is the "I live in Los Angeles" statement. Heavy traffic, stop-go/grid lock will absolutely kill fuel economy. 0 MPG while stopped for long periods see to that.
  • yul711yul711 Member Posts: 8
    I live in NYC and also have my share of bad traffic, although may be not as bad as in LA, but my mpg is still significantly better than yours (no bragging here, just a comparison statement). In general, I'd suggest try perform some maintenance/service/repairs step-by step to eliminate problems starting from the cheapest one, and try to estimate mpg changes (if any) after each step. Hopefully, somewhere along the way you may get a some mpg improvement. That is what I'd do if I was badly disappointed with my mpg. In my case, the spark plus replacement helped a lot and coils/wires replacement may be next.
  • LASHAWNLASHAWN Member Posts: 303
    I've got the same car with over 82k miles and I'm getting around 19-21mpg in city driving and around 26mpg on the highway. And I've got a lead foot
  • hotrod54hotrod54 Member Posts: 82
    edited November 2011
    Ok, class is in session, listen up. The first thing to remember about the manufacter's claims about fuel mileage...they are EPA ESTIMATES. The EPA ESTIMATES are a guide to compare one vehicle to the next. On the Mulroney sticker, these words appear under both the city mpg and highway mpg...using my car (2011 SE 2.0T) as an example..."city mpg 22, expected range for most drivers 18 to 26; "highway mpg 33, expected range for most drivers 27 to 39". Next, driving type and style. When I was in the service biz, people always complained they did not get the advertised mpg; see above. Upon intense questioning of these people I would determine the type and style of their driving. Here's what we get. In heavy, short distance stop and go commuting, you will not get good fuel mileage. Quick acceleration followed by hard braking will suck gas right down. If your commute is short (less than 10 miles), your engine is just barely fully warmed up, thus, reduced fuel mileage. If it is cold out, your car will consume more fuel. Whenever you are at idle, whether you warm up before you drive (not reccommended for more than 30 sec.), when you run in to the store for that cup o joe and leave the car running, in traffic, at the drive thru, you are getting 0 mpg. If you have the a/c on, you are using more fuel. If you have the defroster on above 35 degrees, the a/c compressor is running, using more fuel. Before you question your fuel mileage, question yourselves, examine how you drive, whether the compressor is running, ambient air temp. etc. Okay, class dismissed. Feel free to pass this info on to family and friends.
  • jordanlevin8jordanlevin8 Member Posts: 4
    Thanks hotrod. I have done the following:

    New Spark Plugs
    New Air Filter
    Put in the fuel injector cleaning solution in my gas tank
    Fixed tire pressure

    I live in LA... So guess my 5 mile commute stop and go is why I get 16mpg... Unless you have any other suggestions...
  • hotrod54hotrod54 Member Posts: 82
    Well, the only other suggestion I have is to ease into the throttle very gently and coast to stops as much as possible. Good luck and you're welcome.
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