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Only 23 mpg with my '02 M6???

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Old 01-21-2003, 07:54 AM
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Default Re: Only 23 mpg with my '02 M6???

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CW 99 Z:
<strong> Dont take this the wrong way Biochem, but I laughed a little when I saw this post. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">No worries... and don't get me wrong, I am happy with what I am getting too. It's just that I am really resisting the urge to mod the hell out of this car like I did with my 84z28, but the fact that I still have 2 yrs left on the warranty(and 3yrs of payments), I have decided to hold off on the big things (cam/heads/nitrous) for now. I'm just a little pissed/concerned that my car... stock... isn't performing as the dealer said it should (i.e.- 28 mpg highway). I'm not dissappointed with the low 13s I clicked off at the track last month though <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Old 01-21-2003, 01:07 PM
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Default Re: Only 23 mpg with my '02 M6???

Why should a comment regarding poor mileage be either chuckled at or ridiculed with the suggestion of buying a Civic? <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

Complaining that a model has poor mileage when it produces 300+ hp and tq is a bit ridiculous, but when a couple of people have individual cars getting almost 20% lower fuel economy than most vehicles of a particular model line, isn't there just cause for concern?

Thanks for the help. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
Old 01-21-2003, 02:16 PM
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Default Re: Only 23 mpg with my '02 M6???

Mpg has alot to do with how the car is driven. Also has to do with the terrain your driving in. As an example, When I moved to TN from Virginia I kept track of my mpg. From VA to around Ashville NC I got 31 mpg. Its mostly flat Highway until you get near Ashville. Stayed over night there and drove to Crossville TN next day. Only got 26 mpg. This is mostly mountain driving. Had the cruise set at 60 both days(following a U-hual) My point is, I might be able to drive his car and get 30 MPG, or I might drive it and get 20 mpg. Theres just to many variables to worry about a couple mpg. If it was like 15 I would say get it looked at.
Old 01-21-2003, 08:58 PM
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Default Re: Only 23 mpg with my '02 M6???

If you want try this to get an acurate milage count. Near the freeway stop at a gas station & top off the tank when the pump automaticly shuts down the first time stop putting fuel in. Reset trip odometer. Go down the highway w/cruise set for 15 or so miles. Then use cruise control on the way back to the same gas station same pump. Add fuel to tank until it automaticly shuts down this will give you the amount of fuel used (on the pump) & your trip milage you'll get an acurate measure of milage.
Old 01-21-2003, 09:50 PM
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Default Re: Only 23 mpg with my '02 M6???

Ok, here's my case. I drove a full tank from Sterling, IL to Decatur, IL and then did the return, 23mpg down, 22 up. Gas stations on the edges of both towns, nearly all 6th gear.

Central Illinois is flat as can be. I ran through full tanks to get the best "average." Numerous receipts since that trip have been consistent with those measurements. Never over 23mpg.

The car gets relatively bad mileage consistently, even in 6th gear. It's a fact. No tricks, no terrain, no hard acceleration, no stops. No one has any answers.

The car dyno'd well. 323hp, stock. Air/fuel ratio was good according to the exhaust measure. Dealer won't look at the car.

I'm lost as to the cause, but it's a bit frustrating hearing dealers tell me to wait till 10,000 miles, hearing other drivers get 28-30mpg, and hearing other people tell me that with concern about 15%-20% worse mpg, perhaps I should drive a Civic.

Further, it's insyulting that people think I can't figure out MPG.
Old 01-21-2003, 10:24 PM
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Default Re: Only 23 mpg with my '02 M6???

23mpg is just fine in my book <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Old 01-22-2003, 08:09 AM
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Default Re: Only 23 mpg with my '02 M6???

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by absolut_speed:
<strong> Ok, here's my case. I drove a full tank from Sterling, IL to Decatur, IL and then did the return, 23mpg down, 22 up. Gas stations on the edges of both towns, nearly all 6th gear.

Central Illinois is flat as can be. I ran through full tanks to get the best "average." Numerous receipts since that trip have been consistent with those measurements. Never over 23mpg.

The car gets relatively bad mileage consistently, even in 6th gear. It's a fact. No tricks, no terrain, no hard acceleration, no stops. No one has any answers.

The car dyno'd well. 323hp, stock. Air/fuel ratio was good according to the exhaust measure. Dealer won't look at the car.

I'm lost as to the cause, but it's a bit frustrating hearing dealers tell me to wait till 10,000 miles, hearing other drivers get 28-30mpg, and hearing other people tell me that with concern about 15%-20% worse mpg, perhaps I should drive a Civic.

Further, it's insyulting that people think I can't figure out MPG. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That's basically my question too. I'm not dissatisfied with the power the car puts down, but considering I have yet to dig into the motor, I am a little curious as to why I get less milage then others with 4.10 gears and a T1 cam <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

It isn't because of tire pressure... it's at 40psi for the last trip.
It isn't because of terrain... trips across NC and up to VA (both flat) both give the same results.
It isn't because of romping on the gas... I made intentional efforst not to do that during the last two trips.
It isn't because of mods... there aren't any.
It isn't because my engine isn't "broken in"... it is at 12K, but has been this way since I first bought the car new.
It isn't because of outside temps... trips were in the summer and winter.

At least I can take solice to know that my car isn't a total freak when it comes to mpg <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Old 01-22-2003, 09:22 AM
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Default Re: Only 23 mpg with my '02 M6???

With regards to the dealer not lookin @ the car, take it to a new dealer! If its under warranty, and you bought it from them, and they still wont look @ it, then they're bending you over...

Whether its the next day, next week or next year, the dealer should honor the fact that its under warranty (which im assuming it is) and look it over. Whether they feel it'll break in @ 10k or not. Thats their job...and if i were you, i'd take it to another dealership and see what they say.
Old 01-22-2003, 09:28 AM
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Default Re: Only 23 mpg with my '02 M6???

It could be worse... I only get 15mpg <img border="0" title="" alt="[Razz]" src="gr_images/icons/tongue.gif" />
Old 01-22-2003, 02:21 PM
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Default Re: Only 23 mpg with my '02 M6???

I have seen the same thing except not with LS1's. I had two diffent Neon's nothing diffent about the two either. One would get 5mpg more than the other! The dealer could find nothing wrong with it either.

On the LS1, I can get 19-20 in the city with my M6, I drive very easy, nothing over 2300rpm between shifts. On trips I have got over 25 as well even going 70-90mph.

One thing I learned is that if the throttle body gets dirty, it effects the gas mileage pretty heavily. If you see a lot of carbon or dirt where the blade touches the floor of the TB when it is closed, clean it. I alway shoot a little carb cleaner in there when I do an oil change. Keep it clean and you will notice a difference. I have done this on many cars and have seen big changes, over 3-5mpg. I got this tip from a guy that worked at a shop years ago and it helped.
Old 01-22-2003, 02:22 PM
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Default Re: Only 23 mpg with my '02 M6???

I have seen the same thing except not with LS1's. I had two diffent Neon's nothing diffent about the two either. One would get 5mpg more than the other! The dealer could find nothing wrong with it either.

On the LS1, I can get 19-20 in the city with my M6, I drive very easy, nothing over 2300rpm between shifts. On trips I have got over 25 as well even going 70-90mph.

One thing I learned is that if the throttle body gets dirty, it effects the gas mileage pretty heavily. If you see a lot of carbon or dirt where the blade touches the floor of the TB when it is closed, clean it. I alway shoot a little carb cleaner in there when I do an oil change. Keep it clean and you will notice a difference. I have done this on many cars and have seen big changes, over 3-5mpg. I got this tip from a guy that worked at a shop years ago and it helped.
Old 01-22-2003, 08:22 PM
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Default Re: Only 23 mpg with my '02 M6???

I don't know if the civic is the answer.My girlfriend just got an 03 civic that is supposed to get 30/38 mpg but has only seen a best of 33.5 so far,usually more like 31-32.This is a 45 mile trip each way to work with only 15 of it off the highway.
I am not impressed.Honda dealer must be in with the chevy dealer cause the also say bring it back later,not broken in.
Hoping the LS1 I am putting in my 73 camaro will get 25 mpg,I'd be happy.
Old 01-23-2003, 12:32 AM
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Default Re: Only 23 mpg with my '02 M6???

You guys keep raggin the dealers because they wont fix your car and I realy dont think its justified. I worked at a chevy dealership for a couple of years so I've got a little more insight than some of you. As far as warranty goes, the dealership has to clear everything through GM. The dealership does the work and GM pays them. If they work on something GM wont clear, they dont get payed. The techs also get paid for less time to do the job under warrenty than they would for a paying customer. The hourly rate is increased a little but it doesnt begin to equal out. I'm just guessing, but I would think they would give the tech one hour diagnostic time. First thing he would do is check to see if there were any tsb's on the problem. Then he would hook the tech II up to it to make sure the O2's are swithing correctly, and check the maf and tps values. Probly check the fuel pressure too. If everything checks out OK, hes not going to work on it for 3 or 4 hours if he only gets paid for one. Also, heres a tip on trying to get them to look at it. Dont go into the shop with the attitude that they are the enemy. Also, dont go in there with the attitude that you know more than they do, even if you do. This will **** them off more than anything and they will try their damndest to not help you out. I'm not saying you guys did this, I'm just speaking from experience. The bigger dealers are also more likely to stick thier neck out for you because they can afford to "eat" more than a smaller dealer can.
Old 01-23-2003, 01:12 PM
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Default Re: Only 23 mpg with my '02 M6???

I appreciate the advice, but I mentioned the dealer, but in no way did I "rag" them. I called my service advisor, informed him of the problem, told him I had records of the poor fuel economy and asked for an appointment. The service advisor had me speak with a tech who told me that the motor's aren't completely broken in until 10,000 miles, so there's not much they could do until then. I left it at that. The dealer is also one of GM's better sales dealerships in the midwest, and have built a brand new facility in the last year.

As for another dealer, that's easier said than done, especially when you're not in or near a metro area.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CW 99 Z:
<strong> You guys keep raggin the dealers because they wont fix your car and I realy dont think its justified. I worked at a chevy dealership for a couple of years so I've got a little more insight than some of you. As far as warranty goes, the dealership has to clear everything through GM. The dealership does the work and GM pays them. If they work on something GM wont clear, they dont get payed. The techs also get paid for less time to do the job under warrenty than they would for a paying customer. The hourly rate is increased a little but it doesnt begin to equal out. I'm just guessing, but I would think they would give the tech one hour diagnostic time. First thing he would do is check to see if there were any tsb's on the problem. Then he would hook the tech II up to it to make sure the O2's are swithing correctly, and check the maf and tps values. Probly check the fuel pressure too. If everything checks out OK, hes not going to work on it for 3 or 4 hours if he only gets paid for one. Also, heres a tip on trying to get them to look at it. Dont go into the shop with the attitude that they are the enemy. Also, dont go in there with the attitude that you know more than they do, even if you do. This will **** them off more than anything and they will try their damndest to not help you out. I'm not saying you guys did this, I'm just speaking from experience. The bigger dealers are also more likely to stick thier neck out for you because they can afford to "eat" more than a smaller dealer can. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">
Old 01-23-2003, 01:54 PM
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Default Re: Only 23 mpg with my '02 M6???

Ugh. Don't talk to me about gas mileage. I went from 22-23 MPG average with my M6 to 18 MPG, highway only, when I put in the A4. Stupid 3.70 gears! <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" />
Old 01-23-2003, 03:10 PM
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Default Re: Only 23 mpg with my '02 M6???

WOW, lets see if I can make sense of all this... You own a (almost) showroom stock 12 second capable car that gets 20+ mpg, and your wanting more??? The dealer is supposed to take into account all of your driving habits and other factors that affect gas mileage and "SEARCH?" your vehicle for the reasons why one car/driver combo is more fuel efficient than another? <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" /> There is a q-jet around that made good horsepower and was fuel efficient-Just the words "Quadra-jet" make me think of the days of the 400 ci/190hp late 70's Trans Ams...Man, those were the days <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Old 01-23-2003, 05:33 PM
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Default Re: Only 23 mpg with my '02 M6???

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Stu'sWS6:
<strong> WOW, lets see if I can make sense of all this... You own a (almost) showroom stock 12 second capable car that gets 20+ mpg, and your wanting more??? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well Stu... Yes. Should I not be concerned that something I spent $20K+ for is not working as promised? Should I not be concerned that something I spend a lot of time taking care of for some reason is not working as well as it is supposed to? Why am I not getting the milage I should be getting? What else am I not getting... like the 300+HP that they promised too? Who should fix it if it is broken... me? That's not what I paid a lot of money to have to do.
Old 01-24-2003, 09:01 AM
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Default Re: Only 23 mpg with my '02 M6???

when i had 3.23s my car got 21 on the highway, rompin on it a bit. car had a cam in it too. its an auto too. i think you should be able to do better. heres a tip, when going up hills let off the gas a little. keeping the cruise on will hurt your milage if you arent on flat ground.

on a sidenote, from texas to chicago i averaged 15.5 mpg on the highway in a tahoe with 3.73s at an average speed of 90-95 mph. i think thats decent considering how NOT aerodynamic tahoes are <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> its a 97 fwiw. rpms were turning about 2400 i think.
Old 01-24-2003, 01:09 PM
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Default Re: Only 23 mpg with my '02 M6???

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Stu'sWS6:
<strong> WOW, lets see if I can make sense of all this... You own a (almost) showroom stock 12 second capable car that gets 20+ mpg, and your wanting more??? The dealer is supposed to take into account all of your driving habits and other factors that affect gas mileage and "SEARCH?" your vehicle for the reasons why one car/driver combo is more fuel efficient than another? <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">So many people are missing the point. Poor gas mileage relative to other cars of your model can be indicative that there is something amiss. I'm certainly not complaining about the power/mpg ratio, but if my car is new, and underperforming in some way, I think I'm justified in finding an answer. Sorry for the rehash, but some people must be thick.

Why is it so hard for people to understand that?
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Old 01-24-2003, 03:21 PM
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Default Re: Only 23 mpg with my '02 M6???

I wonder how common this problem (low MPG) is and if it is mainly the '02 models? A friend of mine bought an 02 SS M6 and can't get 200 miles on a tank to save his life. Like others that posted, he asked the dealer about it and they said they can't do anything until it's broken in.
(also, the service guy said the car is programmed to run on lower octane gas, and that my friend's use of 92 octane fuel is contributing to the low MPG)



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