New Pontiac G6 4-banger is a guzzler

Discussion in 'GM' started by somedude, Sep 16, 2008.

  1. somedude

    somedude Member

    Hi everybody,

    Has anyone had any experience with the LE5 Ecotec engine? After almost 5000 miles I still get lousy mileage and I drive very conservatively (give the price at the pumps) and I use a Scangauge to monitor it as well.
    The 2.4l VVT engine isn't supposed to burn 11-12l/100Km; for city driving they claim 9.6.
    I figured until the engine loosens up a bit, that's normal, but it's still about 20% higher.

  2. phoebeisis

    phoebeisis Well-Known Member

    You are getting about 20 mpg? What sort of driving do you do?
    All city?
    How far is your average trip?
    Cold climate?
    Tire pressure?

    The old- "motor will loosen up with age" is from another time with poorer machining and quality control. Engines break in very quickly now-few hundred miles- and the improvement with break-in is not going to be over a few percent anyway (now). In the old days it took a while for rings to seat etc, so your mpg might improve for the 1st 5000 or so miles. Now what you get at 1000 miles is about what the motor/drivetrain is capable of.

    Let us know what sort of driving you do.
  3. ksstathead

    ksstathead Moderator

    Pump to max sidewall and NICE-on P&G instead of steady granny acceleration to steady state and see what you get. Is it an auto tranny?

    You should get at least 120% of city epa if typical trip > 2-3 miles, in my experience.

    Highway should also exceed that epa rating by 20% or so at say 62mph DWL.

    Good luck & report back.
  4. aca2983

    aca2983 Well-Known Member

    It took at least 7500 miles for my Mazda3 to break in, and that is the typical time reported on various online forums, as well as this one.
  5. 2008Mazda3i

    2008Mazda3i Well-Known Member

    My mazda 3 was the same first tank was only 23 mpg and I thought something had to be wrong but my mpg continued to go up almost every tank until the car finally broke in around 7500-8000 miles.
  6. ksstathead

    ksstathead Moderator

    So its maybe a rotary engine break-in period?
  7. aca2983

    aca2983 Well-Known Member

    Ha ha. In case you're not joking, the Mazda3 has a choice of 2 different 4-cylinder piston engines.
  8. somedude

    somedude Member

    Some answers:
    - driving pattern: all city, with some 50mph areas as well
    - I get this kind of mileage for 20mile trips, less is even worse, I get 15l/100Km for short 1-3 mile trips
    - it's not cold, it's colder that it was this summer, but the daily average is in the high 60s
    - tire pressure about 5-10% higher than specified
    - automatic tranny, the 4 speed one
    - I usually accelerate lightly, short and hard accelerations make my Scangauge hum (the instant fuel consumption reading goes nuts)
    - highway driving is closer to the rated consumption, but still 10% higher
    - I currently have 5k miles on it

    Sorry I took so long to reply, I was out of town.

    Thank you all for responding.
  9. ALS

    ALS Super Moderator Staff Member

    Are you running (E10) Ethanol gas. Makes a big difference in gas mileage.
  10. brick

    brick Answers to "that guy."

    Does the engine temp read normal? I have seen a busted t-stat keep an engine in perpetual open-loop, profoundly impacting mileage.
  11. psychojuggalo17

    psychojuggalo17 Well-Known Member

    hmm, i think i agree with the couple hundred mile break in period. my civic had 600 miles on the clock n i was getting 35mpg without that much hypermiling. got close to 50 on a stint from MT to LA. just over 5300 miles now and not much difference in FE, wouldnt mind if it went up after 7500 miles tho :p
  12. somedude

    somedude Member

    Here are some more answers:
    - I run regular gas that has some additive, probably ethanol, but I have no idea how much. Regular Canadian 87 octane gasoline. About 5 bucks a gallon. :-0
    - engine temps are normal and definitely not open loop (I have a ScanGauge II).
    The thermostat idea is good. I will set the gauge to show instant temp readings.

    I also agree with the short break in period. I actually experienced it myself, as right after I got the car it was horrendous on gas. Plus, we are talking about an engine built in the third millennium... However, I am still hoping that it's going to get better, 'cause otherwise I will put a Suzuki Swift in it...
    The engine, according to what I read, is designed by Lotus (it's the LE5 Ecotec 2.4L VVT). I don't know how Europeans design their engines as far as break-in, but there are so many of them on the road in North America, I hoped other owners of this engine could provide some input.
  13. somedude

    somedude Member


    Thermostat seems fine. Engine goes into closed loop quickly and temperature starts to climb quickly. A stuck open thermostat would keep temperature low for a while, so I think it's fine.
  14. jkp1187

    jkp1187 Well-Known Member

    Are there a lot of hills in your area, maybe?

    My father had an '06 Pontiac G6 4 cyl a year or two ago, and he was getting around 23 MPG average. He lives in a rural area. (As an aside, six months after he bought it brand new, the car caught fire for no clear reason in his driveway one spring day. GM called it an "act of god". I think they're still fighting with his insurance company over it.)

    My wife has a G6 GT (6-cyl) and in mostly city driving, she's getting around 21 MPG.
  15. somedude

    somedude Member

    Not, not really, but it's not flat either. Not like San Francisco, but there are some slopes here and there.
    Not very encouraging news, though. That's why I got the 4 cylinder, hoping to save on gas.
    And facing the perspective of the darn thing catching on fire for no reason... Not good either.

    If it caught on fire, I can only think of three things that can get hot enough: engine, exhaust and brakes. I'm surprised they couldn't figure out the source of ignition. Of course, insurance will cling on to anything so that they don't have to pay.
  16. jkp1187

    jkp1187 Well-Known Member

    99% sure that it was a fuel problem. The car actually stopped and started on its own before it caught fire -- he drove it home and was waiting for a tow truck when it caught fire. Everything on the engine's side of the firewall was consumed....the tires even melted into his driveway. Good thing he hadn't park in the garage, that's for sure -- the flames were shooting up pretty high. His insurance company covered it under his comprehensive, and he actually made money on the deal, because he paid invoice, but the insurance company gave him MSRP when they totalled it.

    FWIW, he lives in a hilly area, even though it's rural, and I can't testify to how aggressive a driver he is.

    That said, I'm not sure your MPG is really that low, considering you're doing mostly city driving (EPA rates it at -- what? 10.7 KM/100L for city, per Do you have a 4-speed automatic or the 6-speed automatic?
    Last edited: Oct 9, 2008
  17. somedude

    somedude Member

    4 speed (I'm a cheap bugger), plus, the 6 only comes on the GT or GTP, I think. Mine is a SE.
    The rating in metric is actually 9.6 city and my driving is not 100% stop and go.
    Plus, I thought 12-13 l/100Km is still too high.

    Good thing it all worked out in the end. You never win with the insurance. I was rear-ended a while ago and I ended up having to pay "betterment" for the exhaust. It was only 250 but they wanted about one grand for everything. I guess I got off easy due to a technicality.
  18. jkp1187

    jkp1187 Well-Known Member

    Got it. I wasn't sure of the 6 spd auto was available for 4-cyl G6's yet. (I know that Chevy does have the Malibu--the sister car--available with a 4 cyl/6 speed auto now. But, now that I think about it, it's probably limited to the high line LTZ model....)

    Is that from a Canadian regulatory board? The number I got was from the EPA website, (They provide a conversion into metric.) Looks like the EPA's numbers were a bit more in striking distance of your observed figures. Still, you're getting lower FE than expected, no doubt.

    Not sure what "betterment" is, but it sounds like you got off from having to pay too much. Good thing.

    I know you have Scangauge, but have you used the G6's computer to check your fuel economy at all? I found it to be, well, wildly optimistic to say the least. On a recent trip to Virginia, it said we were getting around 30 MPG...but when I filled the tank, it turned out that the real number was around 24 MPG.
  19. somedude

    somedude Member

    Well, I had to adjust the ScanGauge to match up with the car's computer, but mine was very close to the actual, considering that there is no good way of filling up the same way every time.
    I kept an eye on it for a few months and it was pretty close. Close enough to trust ti, anyway. Then the gauge needed a slight speed adjustment and now they are almost identical readings, within a tenth or two.
  20. safooma

    safooma Member

    I owned an 06 g6 with the 2.4/4spd auto for two years and 50k miles. The milage did get better after 10k miles--but it was never as good as I thought it should get. My daily drive was 30 miles(80% hwy) one way and my average mpg was about 26. If I hypermiled it, I could eek 29-30 out of it. The best milage I ever got was on a non-stop trip to seattle. I followed the posted speed limit exactly and didn't stop once and got 33.8 mpg.

    However, 20mpg is bad. My wife used to deliver pizzas in the G6 for a while and she usually got 23 mpg doing that. What could be worse for milage than delivering pizzas?

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