: northstar poor mileage



Sixstring
02-27-08, 08:18 PM
Recently purchased a 2001 STS with 80k miles. Car is in excellent condition in and out. Factory 17 inch wheels, runs and drives very nice. Info I have found indicates highway mileage is 27 mpg average. Have changed plugs, and air cleaner, best mileage to date is about 22.5 with cruse set at 74. I do see the occasional P0420 code indicating 0s sensor or cat converter. Any suggestion?

Thanks
Dan

codewize
02-27-08, 09:35 PM
I'm sorry but I think someone is smoking something there. There's no way in hell anyone is getting 27 with a VIN 9 N*. It's just not happening.

Most of us are seeing between 20 and 22 at best. My DTS averages about 18 with a 50/50 mix of city and hi-way driving. Maybe if you drove on a hi-way at 60 downhill for 9 hours you could average 27 MPG.

On a road trip I can average 23 - 25 but that's exclusively for that trip and that's never getting into it and just about costing the whole time.

Now the VIN Y N* will get a little better fuel economy but I still think 27 is a very long stretch.

I'm not sure on the code but I can tell you that O2 sensors are almost never at fault. It's usually something else making the exhaust lean or rich like a post MAF vacuum leak.

JimD
02-27-08, 09:59 PM
....I do see the occasional P0420 code indicating 0s sensor or cat converter.There is no "or" with codes.

P0420 - Catalyst System Low Efficiency
This deserves more systematic diagnosis.

Fuel economy of 27 MPG highway "average" is a fairy tale for a 4,000 lb car. It might be possible at 50 MPH (do you really want to drive at 50 MPH on the Interstate highway system?). Not for me.

Murphyg
02-27-08, 10:07 PM
The fact that that he's complaining that it is bad is what really baffles me.
Isnt that close to what these compact eco friendly hybrids get LMFAO

"Thank You Sir May I have Another"

LOL

NHRATA01
02-27-08, 10:44 PM
Weight is not a very big factor at highway speeds, drag affects the mpg alot more. FWIW I have pulled just under 27mpg in my SLS on extended highway trips going about 70-75, so it's certainly feasible. Around town if I don't goose it too much I can get about 19mpg.

Murphyg
02-27-08, 10:47 PM
But your not complaining. AND your in an 03
Sure may be feasible, but holly cow....what is expected......complaining about that mileage in an 01 ????

Sixstring
02-27-08, 11:18 PM
Ok now..the original window sticker, which I have shows 17 city / 27 hwy. Have read more then a few reviews and all indicate 26-27 average on the hwy. Havent smoked anything in 20 years, if 22.5 or so is average then I am not complaining. However...I have spent 20 plus years building automation for the big three and find it hard to believe that the sticker would be incorrect. Also Neighbor has an 02 SLS and drives to sunny FLA in the winter, he claims 25-26 highway.

Murphyg
02-27-08, 11:30 PM
Ohhhhhh !!!! The sticker !!!!

I understand now

ejguillot
02-28-08, 12:21 AM
It's not just the sticker, I averaged 21.1 mpg for an entire tank (calculated by miles driven/gas pumped, not by the onboard computer). That includes at least 1/3 city driving.

Now, I got that average by very gentle acceleration (from a red light, car will shift up at 2000-2200 RPM), using the cruise control wherever possible, 39PSI in the 4 tires (good for fuel economy, not so good for everything else), and a fresh wax job (paint feels slick to the hand, that should decrease aero drag a tiny bit).

Using the cruise control on the interstate, I have seen a steady state 24-27 mpg at 80, and 27-30 at 68, and 30-32 at 60. I think that's as good as a VIN 9 Seville is going to get.

And I get the p0420 code too, just haven't had time to dig into that in detail (car will set code about twice a week, and no other codes are set).

TexasCadillac
02-28-08, 01:59 AM
The people who get the best mileage are usually on flat ground. Hill country sure make gas mileage drop.

codewize
02-28-08, 11:18 AM
Ok that's cool. I didnt look the code up and was assuming it had something to do with lean or rich.

sorry :o


There is no "or" with codes.

P0420 - Catalyst System Low Efficiency
This deserves more systematic diagnosis.

Fuel economy of 27 MPG highway "average" is a fairy tale for a 4,000 lb car. It might be possible at 50 MPH (do you really want to drive at 50 MPH on the Interstate highway system?). Not for me.

dwight.j.carter
02-28-08, 11:19 AM
Recently purchased a 2001 STS with 80k miles. Car is in excellent condition in and out. Factory 17 inch wheels, runs and drives very nice. Info I have found indicates highway mileage is 27 mpg average. Have changed plugs, and air cleaner, best mileage to date is about 22.5 with cruse set at 74. I do see the occasional P0420 code indicating 0s sensor or cat converter. Any suggestion?

Thanks
Dan

the only way you will get that kind of milleage is going 55mph with the air conditioner turned off. Mine did that good when I had to do it.

codewize
02-28-08, 11:24 AM
I agree, it's just not happening. Maybe just maybe on flat ground as mentioned with no AC babying the car from every single stop on a long road trip you might get 26 or 27.

Maybe back in 01 under ideal conditions that car did once get 27 on the hi-way but I can assure you that you'll never see that.

BTW window stickers are wrong quite often. Have you looked at a Prius lately? They claim insane mileage and my inlaws have had 2 of them, brand new, that don't come close to the claims on the sticker.

I would expect 24ish on the hi-way with an average of about 18

dkozloski
02-28-08, 11:27 AM
The way to get exceptional fuel milage like the other guys do is to do the same as they do; lie about it. About all you can do is keep the tires aired up, slow down, and drive like there's an egg between your foot and the gas pedal. The biggest single factor is not the car but the driver. Back in the days of the Mobil Fuel Economy Run it wasn't the same cars that won year after year, it was the same drivers.

Submariner409
02-28-08, 12:21 PM
17/27 is the EPA test figure, + or -, on level ground, with 1/2 tank of gas, no load, 55 mph. It's a government fairy tale lobbied by the manufacturers in order to keep ahead of CAFE.

Mileages have been posted in here for years.....My late '02 STS, 2 people, luggage, highway = 23.9 mpg, 87 octane, MD to FL and return, 70 or so on Rt.95. In town/rural, 16.5 - 18.5 mpg. I also have the original sticker; 17/27.

Sevilles and Eldorados vary all over the place in mileage, due to final drive ratios, gas formulation, locale, driving habits, and mechanical condition.

NHRATA01
02-28-08, 01:10 PM
The way to get exceptional fuel milage like the other guys do is to do the same as they do; lie about it. About all you can do is keep the tires aired up, slow down, and drive like there's an egg between your foot and the gas pedal. The biggest single factor is not the car but the driver. Back in the days of the Mobil Fuel Economy Run it wasn't the same cars that won year after year, it was the same drivers.

Absolutely, alot has to do with the driver. I wouldn't call NY totally flat ground, but if you try to play the hills to your advantage - pickup speed on the approach, allow a 10-15mph drop on the ascent, and coast on the decent - I don't think 27mpg is excessive, at least for the SLS's. The shorter final gear of the STS is probably going to cost you a few mpg easy on the highway.

Similarly, when my 6 speed T/A was mostly stock with a few bolt ons, I once touched 30mpg on a 6 hour drive at a steady 70mph in a car that was putting down about 320 at the wheels. 0.5:1 OD gear sure helped!

Chicano-Mexicano
02-28-08, 02:55 PM
Fuel economy of 27 MPG highway "average" is a fairy tale for a 4,000 lb car. It might be possible at 50 MPH (do you really want to drive at 50 MPH on the Interstate highway system?). Not for me.

My 93 4.9 eldo pulls 30 on the highway and that calculated after fill up not with the computer, so it's not a fairy tale it's just not common.

codewize
02-28-08, 04:51 PM
30 MPG? I'm really having a hard time believing that. The 4.5 and 4.9 are very very similar and my 4.5 STS has never ever in it's life gotten better than 20.

I've had the car since 70 k and I have always gotten around 18 or so.

dkozloski
02-28-08, 05:17 PM
My 93 4.9 eldo pulls 30 on the highway and that calculated after fill up not with the computer, so it's not a fairy tale it's just not common.
It's time to switch the units back to English from metric.

Submariner409
02-28-08, 05:22 PM
I believe the OP has a 2001 STS, which is a N* installation VIN 9 with 3:71 final drive.

To compare that car's mileage figures to any other car with any other engine and final drive ratio at any other time is smoke and mirrors.

Based on many posts in here, the N* SLS VIN Y with 3:11 final drive enjoys about a 10% better mileage advantage over the STS: 2 to 4 mpg.

Chicano-Mexicano
02-28-08, 06:26 PM
30 mpg on the highway sorry I average about 15.5 to 16 in the city (it's winter hear so mileage takes a hit)

JimD
02-28-08, 06:32 PM
30 MPG? I'm really having a hard time believing that....Me too, but every once in a while it is possible to fall into just the right conditions. :bsmeter:

http://s70.photobucket.com/albums/i101/JimDphotobucket/?action=view&current=DSC01791.jpg

Chicano-Mexicano
02-28-08, 06:39 PM
hey talk to any 4.9 owner and they will tell you that you can expect any were from 26-30 mpg on the highway though 30 is on the high end. I've manage to duplicate in only once (the first was on my 260+ mile drive back after getting the car in Michigan) but I usually get about 27 or so on the highway so if my 4.9 can do it no reason a N* can't if their as great as people claim they are. :hide:

Sixstring
02-28-08, 07:59 PM
Hay, Thanks to all who have taken the time to give me some feed back. Seems to be a mix of reply but overall I am thinking that 22 plus is not too bad considering the ride. Just put on new tires, ouch. I drive 150 miles a day round trip for work and the winter has been nasty this year in MI. Going to have the catalitic converter and o2 sensors looked at to resolve the 470 code. Hope to see some improvement after I replace the cat.

codewize
02-28-08, 08:32 PM
Was that down a hill with an 80 MPH tail wind? LOL. No, seriously, I've seen it too but it's never going to be an average over a trip.



Me too, but every once in a while it is possible to fall into just the right conditions. :bsmeter:

http://s70.photobucket.com/albums/i101/JimDphotobucket/?action=view&current=DSC01791.jpg

fubar569
02-28-08, 09:43 PM
funny you guys fuss about mileage...i have NO PROBLEMS getting a VERIFIED (by calculations after fill) 30mpg highway out of my 97 Deville. No lies, no BS...it peaked at 32.5mpg on a very long 300+ mile trip but it was all 4 lane interstate and relatively flat. Typical mixed mileage is 22-25mpg and i have seen 19 city mpg before also...i maintain it well with Rotella Oils, do routine maintenance, maintain good tires, O2 sensors, etc...I also tend to err on the LOWER side of the speed spectrum (since speed limit up in this area of PA is only 55mph)...i am usually NO MORE than 5mph over the limit, sometimes i set the cruise right at the limit and let it go...

check in on wydopnthrtl? (sp) - he documented a trip from michigan to florida i believe in his 02 eldorado and pulled...i wanna say very high 20's for mpg...it certainly is possible to do, but depends more on the driver and care than the individual car & motor...

BUT...FWIW my dad in his 02 Deville cannot seem to break 28 no matter what he does...under any circumstances. i do get better mileage than him in his own car but it still does not have the range my 97 does for long trips.

Murphyg
02-28-08, 09:47 PM
Absolute optimum conditions.
No stop and go whatsoever. No other traffic at all for that matter.
No hills, valleys, pot holes, different road surfaces, or even weather conditions. Wind, temperatures etc....
If those stats even come from testing outside I would be surprised.

Its probably all done on a dyno. No turning or road force etc....

Not to mention that the fuel they are using doesnt come from the gas station across the road.

Another thing Ive noticed as well with those sticker mileage things.
In Canada we are on the liter system. But they still show mpg as well on the sticker.
When I was looking at my 01 I took a close look at some of the stickers on the vehicles in the show room and did the math between the mpg and kilometers per liter.
For some strange reason the math didnt work out. So I asked.
Liters and kilometers are standard throughout the world. But it turns out that gallons are not. Apparently the American gallon is larger than the Canadian gallon. So when all us Canadians are looking at the stickers on American cars we are given a false measurement of actual mileage.
I know that really doesnt pertain to buying a vehicle in the States. But it does show to not believe that what is written on a sticker is actually written in stone. Its all a part of the deceptive marketing to draw in the consumer. Just within the line of what is legal. And to deceive the majority that trust and cant be bothered to protect themselves by asking and becoming informed.

And on a side note note.........Have also heard that an American pound consists of 12 ounces ????
But a Canadian pound has 16 ounces.....
So a word to the weary.....Dont purchase beef or dope in the States. Your gonna get short changed LOL

Murphyg
02-28-08, 09:53 PM
........................... No lies, no BS...it peaked at 32.5mpg on a very long 300+ mile trip ...................

When you say "it peaked at...", are you referring to the DIC readout while being set at "Average MPG" ? Cause there is a very very huge difference between Average MPG and Actual MPG.

JimD
02-28-08, 10:14 PM
....Apparently the American gallon is larger than the Canadian gallon.Sorry, but you have that volume comparison reversed. Your "Canadian" gallon is/was the same as an "Imperial" gallon which is/was larger than the "American" gallon by 20%.
...Its all a part of the deceptive marketing to draw in the consumer. Just within the line of what is legal. And to deceive the majority that trust and cant be bothered to protect themselves by asking and becoming informed.Can we talk about being informed for just a minute here?
....And on a side note note.........Have also heard that an American pound consists of 12 ounces ????
But a Canadian pound has 16 ounces.....
So a word to the weary.....Dont purchase beef or dope in the States. Your gonna get short changed LOLAnd exactly where "in the States" do you buy your dope?

Murph:
Take 10 really deep breaths and get your facts in order. Tonight is probably not the best time for you to be typing on the Internet.

dkozloski
02-28-08, 10:35 PM
Gold is sold by the Troy ounce. There are 12 Troy ounces to the pound. Ordinary weight called averdupois is 16 ounces to the pound. The old Canadian quart(Imp) oil can was much larger than the American. The Canadian gallon(Imp) was five American quarts.

Murphyg
02-28-08, 10:36 PM
Sorry, but you have that volume comparison reversed. Your "Canadian" gallon is/was the same as an "Imperial" gallon which is/was larger than the "American" gallon by 20%.Can we talk about being informed for just a minute here?And exactly where "in the States" do you buy your dope?

Murph:
Take 10 really deep breaths and get your facts in order. Tonight is probably not the best time for you to be typing on the Internet.

Just like you quoted me.....I said "apparently".....
I was not making a statement of fact.
Has always amazed me how so many will only hear what they want to here and disregard all else that is actually pertinent.

This is a place for information. A place to learn and expand ones knowledge. I appreciate the fact that you were able/willing to help in that matter. But to belittle someone in the process......????
If one is adamant about what they are saying; then I could understand going that step further to let them know that they are arrogant, close minded, and they are truly not a jack of all trades.

But if you really feel that you know enough on a particular subject to go that way with another. May I suggest that you pay a bit more attention to what that other has actually said.
And if your not capable of that. Then I may I suggest that you dont bother at all conversing with any one. On the Internet or any where else for that matter.

"Apparently" that is the reason as to your reply to my post.

Murphyg
02-28-08, 10:41 PM
Gold is sold by the Troy ounce. There are 12 Troy ounces to the pound. Ordinary weight called averdupois is 16 ounces to the pound.

And again you have been able to teach me something.
What a wonderful place to learn.

Submariner409
02-28-08, 11:28 PM
This is beginning to sound like a CTS thread. (Whine, whine, bitch, bitch, me, me, he said, she said........)

Put everything on the same playing field, level it, and the apples and oranges even out. Pounds, ounces, kilos, kpg, kpl, mpg, gph, blah, blah don't mean squat unless they're all reduced to a common basis for comparison. A pound of feathers weighs a pound, and a pound of bricks weighs 16 oz. A kilo is just about 2.2 pounds. A kilometer is around .62 miles. (I want my MTV, I want my MTV.....money for nuthin', chicks for free....)

JimD
02-28-08, 11:49 PM
Just like you quoted me.....I said "apparently".....
I was not making a statement of fact....Whoops!

"Not makng a statement of fact"! Why not? Can we differentiate between opinion and scientific truth here?

If your post #31 was intended to be funny or sarcastic, I can buy that.

To a point.

Murphyg
02-29-08, 12:07 AM
This is beginning to sound like a CTS thread. (Whine, whine, bitch, bitch, me, me, he said, she said........)

Put everything on the same playing field, level it, and the apples and oranges even out. Pounds, ounces, kilos, kpg, kpl, mpg, gph, blah, blah don't mean squat unless they're all reduced to a common basis for comparison. A pound of feathers weighs a pound, and a pound of bricks weighs 16 oz. A kilo is just about 2.2 pounds. A kilometer is around .62 miles. (I want my MTV, I want my MTV.....money for nuthin', chicks for free....)

ROTFLMAO :highfive:

Heard that song today and remembered when it came out. What a hoot ! And they made millions singing about it. No word of a lie. I was laughing out loud today about that song :highfive:

But seriously though :suspect:
Is the CTS forum really full of individuals just like way back when.....when owning a BMW made them think they were something special.....made them act anal retentive because........well..... I dont know why because......but they sure acted/do act "me, me, me, me" LOL

If thats the case its kinda sad to know that. Cause Im quite sure that wasnt the intention of GM when they finally began competing.
If anything.
Cadillac, and there owners, have always been above that petty shyte.
But then again shyte happens and individuals are individuals.......:stirpot:

So what was the mileage again ???? LMAO

Sorry for upsetting someone by participating and giving an unbiased opinion on a topic. Maybe I should buy a CTS......................DoHHHHHH

Hey Jim ...

No harm no foul :gah:

JimD
02-29-08, 12:19 AM
....Hey Jim ...

No harm no foul :gah:

Agreed.

Except it would be -- no blood no foul.

Murphyg
02-29-08, 01:36 AM
Whoops!

"Not makng a statement of fact"! Why not? Can we differentiate between opinion and scientific truth here?

...........

Why not ?
Cause the forum is for opinions.
What works for one doesnt always work for the other.
There is no scientific truth here. That is not possible in a help forum. The disclaimer of the forum its self states that quite clearly.

So is this the right forum to differentiate between opinion and scientific truth ?
For each there own on that matter, I guess, :histeric:

But still isnt relevant for coming down on someone about a query. Coming down on some one for bringing something up that they had heard and repeating it in a questioning manner :hmm: Quite sorry If It wasnt factual enough and some may have had a problem differentiating between opinion and scientific truth.
(and to tell the scientific truth.....I dont know what or why that is supposed to mean......)






Agreed.

Except it would be -- no blood no foul.

So it turns out we missed each other on the apology posts.

So lets go with what Alice Cooper said. "Only Women Bleed".
And get back to why we are all here. To help each other out with what we know and have experienced. And not to try to out do each other by putting one down with some kinda copper top on there shoulder.
Pay attention to whats being said and stop trying to be some kinda internet freakin hero. :pms:

Submariner409
02-29-08, 11:57 AM
This is more fun than the day the hogs ate Grandma !

dwight.j.carter
02-29-08, 05:58 PM
Just the 08 CTS forums where the eurotrash lovers seem to be coming over to the brighterside of the luxury automobiles lol.
No offense to anyone.

codewize
03-03-08, 04:22 PM
There are just over 28 grams in an oz and just over 31 grams in a Troy oz. The reason for that is you can't buy pure gold.

When you buy a Troy oz of gold it's actually a regular oz of gold with a small amount of other metal in it for durability so if you buy a 1oz Gold Double Eagle coin it will weigh 31+ grams but the actual gold content will be 28+ grams.


Gold is sold by the Troy ounce. There are 12 Troy ounces to the pound. Ordinary weight called averdupois is 16 ounces to the pound. The old Canadian quart(Imp) oil can was much larger than the American. The Canadian gallon(Imp) was five American quarts.