Pontiac G6 Forum banner

21 - 30 of 30 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #21
hmmm. I know how the dealership can be, when addressing problems that are not easy to solve. The first thing out of their mouth is always, "it's your driving style" or "they're all like that" or "it's characteristic of the vehicle."
i went through a similar nightmare with honda a couple years back. But i stayed on them with a vengeance until they corrected every single problem.
As long as it's not to your liking, keep bringing it back. I assume that you are under warranty??
Unfortunately, you may have to do a little leg work yourself, to get them headed in the right direction.

Let's check some things. You have the 3.5 v6 right? yes
does your radio have the trip computer included? yes
what does the display show your avg mpg @ right now? 18.9ltrs per k
using the instant mpg, track what your mpg is at various (steady) speeds.

At a steady 35mph, 50mph, 60mph, 70mph? I've always been very impressed with the 3.5's highway economy. At 65 you should see, atleast 26mpg on the display. 28-30mpg is what i've always seen indicated at those speeds. i will try this

in spirited, city driving. I *always* get 17 or 18mpg indicated by the trip computer. This is on *every* recent gm 3.5, 3.8, 3.9v6 i've driven. If i am more sparing with the throttle, i may see 19mpg indicated for city driving.
So i can see how city mpg could be a little low. But on the highway, these engines, with their healthy low end torque and tall gearing, really shine (rarely falling below 26 mpg avg).

These are things you may have to do (but your dealer should have already):
Jack up each wheel and make sure it spins freely, without drag.
Check your tire pressure.
I'd replace the fuel filter.
Run a quality fuel system treatment through the gas tank. i have not done any of these things to date, but i will try and do by early next week and advise

did this car ever get good mileage? i cannot say, i bought the car with 20,000 k on it and i also owned a f-150 8cyl, i used to drive both. So when i got in one and it needed gas i put it in. But never tracking it. I sold my f-150 and am only driving my g6 and this is the reason i am noticing it now. I also must say that i owned my truck for 6 yrs and only used that for a period of 4 yrs and got way better consumption in it. Interesting fact is i drove my truck the same way that i drive my car. Mostly in town. give it a good listen for any strange sounds from the engine and tranny. Both should be relatively smooth. sounds normal

you say the dealer got 7.8lpk? Whoah! I just converted that... 30.1 mpg!! No way. In the city? That's just bs, for sure. yes... They claimed that it was considered city driving... I told them they were full of crapola... They are not driving it the way that i am and that they cannot tell me they drive 60kms one way to work and not be on the freeway.

i got my best results with the dealer by taking the service technician on a ride with me and pinpointing each of my problems. The ride was not over until he confirmed that he could see/hear exactly what i saw and heard.

Verify that your trip computer is somewhat (they are rarely perfect) accurate. Pick out a test loop (near the dealer). At the beginning of the test route, reset the computer.i have done this and it is almost accurate. Not far off. They did tell me tho that you cannot go by the gages on the dash for mpg/ltrs as they are never correct. Funny thing with this is they are out by maybe 1 mpg when i do thenumbers for consumption from my receipts. at the end, note the mileage. We already know that you're gonna get less than the claimed 30.1 mpg the dealer claimed.
Repeat the procedure, but this time with the dealers tech driving. If there's no problem, his numbers should be considerably higher than yours. And that's with a similar driving style, driving normally, not trying to artificially raise the mpg. i will need to do this as well

but if he get's bad numbers too, pin him down on it and stay on them until they fix it to your satisfaction.

The other thing though... There's gonna be variation in every engine design. In a perfect world all g6 3.5's would get the same mileage under the same conditions. But in reality power, mpg and driveability can vary by a considerably large margin from engine to engine while being in perfectly good shape. Your particular engine may just be one that is gonna deliver low mpg. It happens.

But 11mpg is outside of any margin that could be considered normal. That's extreme. Did it get good mileage before? Ever? see answer above

did you get this car used? yes. Bought it from the dealer with 20,000k on itbeware that there is a good chance that a used g6, may have been a rental car in it's former life. That in itself opens up a whole can of worms. Rental cars get regular service, but they also have a hard service life. uggh... Scary...
they come off the delivery truck and go straight to the rental lot with, often, less than 2 miles on the odometer. Then they are rented and immediately taken on 500+ mile freeway trips non stop. Or they get thrashed around town. A new engine needs a proper break in, if it is to produce respectable mpg, power, and reliability over it's lifetime. Long trips with steady rpms is not good for a virgin engine. High rpm, high throttle is not good for a virgin engine. But this is exactly the kind of service these fleet units see. Even a regular used car may not have been treated well before you received it. Just something to thing about.

So many factors can effect your mpg. Yes, it's gonna be hard to find out what the problem is. But the dealer should acknowledge the problem and be most helpful in resolving it.

Keep us posted.

i wanted to thank you for all your info... I have some homework to do and that is fine..at least i am not going to twiddle my thumbs not knowing what to do cause the dealer is not being helpful. I will post results when i have them.
I have responded to your posting through out it in bold caps so that you can see the answers.

Thanks again :)
 

·
Registered
Joined
·
6 Posts
Hi!

I was jsut wondering if the problem was solved. I'm having the same problem with my 2007 G6 V6 SE. I'm doing about 20L/100 KM (about 11Mpg) and it started to do this about 5 months ago and can't find out why... I used to do about 13L/100KM (I think around 18/20 MPG) and I can't pin point the problem.

Any updates on this situation?

Thanks!
 

·
Registered
Joined
·
470 Posts
Seems odd. I read that you're filling the tank half way. Fill it all the way to get a much more accurate reading.

I get about 400kms on a tank of fuel, with about 1/4 tank left. Most of my driving is in town. I use the autostick regularly (stay within 2500-3500rpm) and the few tanks that I had calculated last year set me in the 12-14L/100km range depending on traffic. Straight highway I can get 600km and if I wanted to, I could squeeze another 100kms in but I like to have a decent reserve. I drove to Pearson airport and back (190km) and I put in 16L to top it up which wasn't bad for a 115km/h stint.

If anything else just do a full tune up on the car. Make sure the air intake isn't blocked, new plugs, tire pressures are at proper pressure, and running synthetic oil can lower frictional loss. I run Amsoil 5W30 full synthetic in my G6 and change the oil every 1-2 years as I only put on about 8-10K miles a year. Not all bad/faulty O2 sensors will throw a code right away either.

It goes to show that it's always good to check your mileage.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #24
Gas Issue

Hi,
The answer is No, I never did get to the bottom of it and then I had enough and sold the car. The dealership could only say that they felt that it was a issue of city driving... :(

Hi!

I was jsut wondering if the problem was solved. I'm having the same problem with my 2007 G6 V6 SE. I'm doing about 20L/100 KM (about 11Mpg) and it started to do this about 5 months ago and can't find out why... I used to do about 13L/100KM (I think around 18/20 MPG) and I can't pin point the problem.

Any updates on this situation?

Thanks!
 

·
Registered
Joined
·
6 Posts
Wow! Talk about good customer service!

Sad to say but this will probably be my first and last american car... or GM... dunno yet. I'll try taking a look at the O2 sensor and see if this fixes at least part of the problem..
 

·
Registered
Joined
·
470 Posts
GM's customer service experience for me was similar, but not over mileage. It'll take a lot for me to get another new GM vehicle. Only reason I went with GM was I had all these GM Visa points, plus the incentives on Pontiac at the time made it a steal. I got what I paid for, ha.
 

·
Premium Member
Joined
·
4,232 Posts
Yea I also got incentives and a nice deal my G6. Second car ever. Also second GM. I've had absolutely no major issues with either car. I'll always be a GM fan, always.

But that doesn't mean I won't buy other makes. I'm looking for a project drift car as soon as my G6 is paid off :D
 

·
Registered
Joined
·
32 Posts
hey goodguy_69, are you still getting terrible gas mileage? I'm in the same situation as you are.. i only get about 120-150kms from full to half with mixed city/highway driving. Let me know.
 

·
Registered
Joined
·
8 Posts
Poor Gas Mileage

I had an 2008 Chevy Impala LT1. I had the 3.5 in it. I got 19 city & 28-34 Hwy. I totaled car.

I bought a used Pontiac G6 SE V6 3.5. I'm getting 14/15 city & 23 hwy. I read all the posts & still don't know why I can't get the same gas mileage as my 08 Impala?

I had it checked out by a few dealers & they can't find anything. It sucks.
 

·
Detroit Playa!
Joined
·
4 Posts
I'm hoping its an ECT sensor that's causing this, I'm having the same issue an have done everything but ECT will try and let you guys know the fix!
 
21 - 30 of 30 Posts
Top