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Pontiac G6: Real World MPG



  • I have a 4cyl and I average 250 miles to a full tank and am getting really frustrated i traded in my gmc envoy for this to save $$$ on gas and so far I am so dissapointed. It has about 5,000 miles and have had one oil change. Dealership kept telling me wait until you hit 3,000 miles then you will see a difference and I havent. The highest my computer has ever shown is 22.7 mpg and that was when i went on a long trip out of town and it didnt get up to that point until I was almost at my destination. I just dont get it, does anyone know what the probelem maybe? I have called GM and no help and the dealership says there is nothing they can do I do not speed i dont slam on the breaks. Any ideas? I cannot imagine getting the gas mileage some of you are getting in the 32's.
  • ajay5ajay5 Posts: 10
    Wow, that mileage is terrible! Wish I had an answer for you.
  • jimtxjimtx Posts: 3
    Does the car seem to be running properly. If it does, you should be getting at least 30 mpg with this car on the highway. In my experience, when someone is getting crappy gas mileage, and the car is running fine, you have to consider that it may be the driver. There are two types of driving that will kill your gas mileage:

    The first type is the lead-foot who drives at high speeds, tailgates, and is always having to hit the brakes to keep from rear-ending the slowpokes. Even if you are not a tailgater, driving at 80mph will get much much worse mileage than someone who drives a modest 60mph.

    The second type of driver who gets poor mileage is one who I have particular enmity towards--that is the people who drive an automatic with two feet, one on the gas and one on the brake. This type will swear that they are not riding the brake, but in fact they are and it will kill your gas mileage.

    A good way to tell if you are either of the above driver types is to ask the following question: How many miles do I get off of a set of brakes? If the answer is anything less than 50,000 (and it should be more), you are either riding the brake or having to brake too often and it will kill your gas mileage.

    If you can honestly say you are not one of these drivers, have the dealer check the car because something must be wrong.

    Just my two cents. Hope it helps.
  • Hi and thanks for info, Im definately neither one of those drivers, I know all the tips that are supposed to help conserve gas mileage and Im very concious of my driving. Im always thinking about the gas mileage, I hate to even pass ppl on the highway b/c i believe it uses more gas. I have taken in and they say all they can do is hook it up to the diagnoistic machine and if it says nothing is wrong then they cant do anything. I have recently been monitoring the mileage when I drive and this is what I have concluded. When I drive on the highway for a long distance, the computer reading for the mpg goes up a point every 8 or 9 minutes. Thats even I am just staedy driving no stopping. It normally reads around 20.5 so if i take a trip thats usually where i am then about 8 or 9 minutes later it would go up to 20.6 then 20.7 and so on. Can you imagine how long it would take me to get to 30?!! I would have to drive to California and I live in Texas. The highest it has ever gotten is 22.9. But as soon as I get back in to town it declines much faster than it goes up. I have no clue how to get them to fix it!!
  • bohboh Posts: 2
    I may have an answer to your mileage dilemma. Axle Ratio! I am looking for someone with more info and data to see if it is the right answer. I am looking to help my daughter buy her first car. (She has been driving one I gave her for the past 4+ years) She wants one of the new G6's. So I began doing some research, and I started test driving the vehicles. I first drove the 3.5 V-6. Then this morning, I drove one of the 4 cyl's. I am looking for the most economical vehicle, but do not want to buy her a vehicle that will not perform over the next 5 years. Gas mileage is important, considering that she is going to be financially challenged, and is starting out a new family of her own. I was making a deal on one of the base models with the 4 cyl, and I noticed the axle ratio for that particular vehicle is 3.91. That set me back a bit. That is the standard axle ratio for that model. That is why the car ran as it did; with quite a bit of power and quickness, when I test drove it. I came home to do more research on axle ratio, without the car salesman following me around. The spec sheet on the G6's shows that they offer 4 different axle ratio's, depending on model and preferred package that is on the vehicle you are looking at. The ratio's available are 3.91, 3.29, 3.05 and 2.77. Not all ratio's are available on all of the vehicles, as far as I can tell. Does anyone know if you can get the 4 cyl. with a lower axle ratio than the 3.91 or not. It seems to me, that any of the other three ratio's would for sure increase the fuel mileage. Any info from someone that knows more about this would be appreciated! Thanks!
  • bud35bud35 Posts: 1
    My 2008 4 cylinder G6 with 3000 miles behaves the same way your car does. The mileage is TERRIBLE. That's why I'm searching the net. Sorry to hear about the dealer experience, I'm bringing mine it tomorrow to have them look for an answer to the mileage issue. I've never had a car that averaged under 25 mpg. I'm getting below 21. ARG. Please post again if you find any answers and I'll do the same.
  • wjtinatlwjtinatl Posts: 50
    I don't own a G6, but travel extensively and get them (and Saturn Aura's) as rentals quite often. My experience is the 3500 V6 will get an average of 25-27 mpg in mixed highway/city driving. Same with the Aura and Impala that share this engine. 4 cylinder G6 and Aura only get 20-21 at best. The earlier post regarding axle ratio is right on, the V6 is relaxed at 2000 RPM at 75 mph, the 4 cyl. runs at 3000 RPM. It's pretty obvious to me that GM created the 4 cylinder G6 and Aura to compete at a lower price point, not to offer a more economical car. However, 4 cylinder or 6, all these mid-size GM products have brake rotors that warp within 12,000 miles.
  • vmsvms Posts: 2
    I have a 2006 3.5L V6 GT. Around town I get 22-23 mpg. When the car was new it got about 19.5 around town in the same commute, and then it slowly drifted up to about 22.5. When I go out on the road I will get up to 29. I wonder if your tire pressure is ok, or if you need a four wheel alignment. With the 4cyl you should get a couple miles better than I do. Do you close the windows when you are on the highway? When I let the tire pressure go down the mileage goes down. I use the mileage indicator to learn when I need to add tire pressure. Otherwise I am not sure what the problem would be. I can bring the mileage down to 19.5 if I stand on the gas all the time. If the mileage stays down, bug the dealer to find out what the problem is. Something is wrong. Best of luck.
  • vmsvms Posts: 2
    Oh yeah, do you shut off the air conditioner when you don't need it? That costs about 2-3 mpg. Good luck.
  • fxr884fxr884 Posts: 1
    Do you reset the MPG before long highway trips or after? Before I go see my girlfriend who lives about 2 hours away, I reset it just before I hit the highway to get a more accurate reading I also reset it again once I get into town. I have the 2006 V6 Sedan and initially i used to see really crappy readings, Im not sure how it was set before I got the car but after I reset it I get around 31 on the highway and about 22 in town. Slowing down does help to I slowed just a little on one of my long trips(usually average 70-75mph) and I got an average of 33.6mpg on that trip
  • packer3packer3 Posts: 277
    There is no problem thats the way it is going to be all the time there is no fix, had a 05 Malibu V6 16mpg was tops in the city and 37mpg was tops for the highway returned it after 23,000 miles it was leased. I went throgh the same thing with the dealer they give you the we cant find anything, however in reality they know the answer, when you talk to other people "live" not blogs, you will find some of your answers.
  • Don't trust the mileage computer to be accurate. Check it by dividing the gallons used into the total miles traveled on the tank of gas. Then reset your mileage and check another tank. The best way to get an accurite reading is run 4-5 tanks of gas and check the mileage using all fuel used and all the miles driven. (IE 75 gallons used in 2025 miles = 27mpg)

    I've seen the mileage computers be off 5 mpg or more.I have a 2004 Chevy truck that was off about 1.5 mpg consistently. It always got about 1.5 mpg less than the computer said it got.
  • gonogogonogo Posts: 871
    Just made a 500 mile trip at 70 mph, some a/c, got 31.5 mpg, I can live with that.
    It was gallons divided by miles.
  • Mine is a 2009 4 cylinder with the 6-speed auto "Sport Package". I already have more than 15,000 miles on it. The mileage with this package is satisfactory. I consistently achieve more than 420 miles per tank and average a little over 30 mpg overall. My work commute is highway, seldom stop and go, making the mileage easier to achieve. I have occasionally achieved 32+ mpg for a tankful (doing the math), but it is usually a little lower. It does not often achieve the EPA rating, but then few cars do in the real world other than hybrids or diesels. The only indicator I watch is miles left per tank; The mpg indicator is only useful to monitor driving habits, not for accurate, achievable measurements.

    For the total package considering size, roominess, comfort, performance, I am reasonably happy. We will see about long term. I am used to taking my cars to 200,000 miles but do not expect that of this car. I have owned mostly VW or Subaru over the years.
  • I have a 2008 Pontiac G6 4-cylinder sedan and I drive short distances. I drive approximately 4-5 miles per day with the longest distance without stopping being 6-10 blocks. I average 14-15 miles to the gallon. The sticker in the car says that I should be getting 22 so they say to figure 2 below that for a more accurate estimate. I am not getting anywhere near this. I average less than 200 miles per tank and it is absolutely ridiculous. I am so disappointed in myself for buying this vehicle. I am going to lose a heck of a lot of money off of it between licensing it and paying to fill it up constantly. :cry:
  • gonogogonogo Posts: 871
    Your drives are too short, get a plug in electric car and your would never need gas.
  • maddog0324maddog0324 Posts: 54
    I have a 2008 4cyl Sedan that I bought used with 19,000 miles in July '09. I now have 43,000 miles. I have been averaging 24.5 mpg per tank, with 80/20 highway/city commute, 10% of the highway miles are stop/go traffic. On the open highway, I always use the cruise control to maintain 8mph above the speed limit. My last road-trip was 735 miles and I averaged 28.1 mpg. My last 90% city driving tankful only averaged 19.2 mpg. I don't go by the on-board mileage average, I divide the miles driven by fuel used. I don't let the fuel gauge go below 1/4 full, because it gets pricey using 93 octane (91 octane is what the owners manual calls for and 91 octane is not available in my area). I am a firm believer that spark-knock will kill the engine. EPA fuel economy is estimated based on optimum conditions, not realistic situations. What percentage is your city/highway driving and what grade gasoline do you use?
  • gonogogonogo Posts: 871
    My 09 2.4 takes 87 octane, right in the owners manual. You better read your manual again.
  • maddog0324maddog0324 Posts: 54
    Your 09 is also compatible with E85 Flex-Fuel, correct? This was not available for the 2008 model year.

    The 2008 owners manual states:

    "If your vehicle has the 2.4L L4 engine (VIN Code B),
    use premium unleaded gasoline with a posted octane
    rating of 91 or higher. You can also use regular
    unleaded gasoline rated at 87 octane or higher, but
    your vehicle’s acceleration could be slightly reduced,
    and you might notice a slight audible knocking
    noise, commonly referred to as spark knock. If the
    octane is less than 87, you might notice a heavy
    knocking noise when you drive. If this occurs, use a
    gasoline rated at 87 octane or higher as soon as
    possible. Otherwise, you could damage the engine. If
    you are using gasoline rated at 87 octane or higher and
    you hear heavy knocking, the engine needs service".

    A 4 cylinder engine would not benefit from reduced acceleration. I also don't want my ride sounding like some beater. Premium unleaded in my area is 93 octane. I will not use a fuel posted 6 octane points lower than recommended. Back in the day, you could get around spark knock by adjusting the timing and fuel mixture. Since cars these days are computer controlled and no user adjustments are available, I'll go with what is stated in my owners manual.
  • gonogogonogo Posts: 871
    My engine is code B, 87 octane. Only 09 that will run E85 is the 3.5 VIN code K.

    It also states the 3.6 VIN code 7 will run better on 89 octane for towing. Everything else in the 09 line up is 87 octane.

    Something must have changed from 08 to09.
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