3.8L... 22 MPG highway? Hmmm.... this just seems strange.

[ChillPhatCat]

I bought my RS (sig) about a month ago, and it's been getting 20 MPG driving up and down the hill between home and work... I figured I'd be getting much better mileage on the highway... I drove 140 miles on saturday, and 120 of those were at 65-75 MPH in 5th... After filling up I calculated 22 MPG for the trip... I pretty much babied the throttle with the intent of seeing what the best mileage to expect was... I was expecting high 20's at least.

Now, when I bought the car it clearly had headers, exhaust and a hurst shifter... no records of any mods. I'm wondering if somethings broke or maybe a cam was installed... There are no leaks and the exhaust smells perfectly clean... If not a cam maybe a chip? It's not burning rich, and it's not making sounds...

I really don't know what the V6 should feel like stock, since I went from a mid 80's low output V8 to this 3.8L V6... When I punch it it pulls pretty agressively... It will take me to 100 with very little effort. But I have no idea what fast (ie LS1) feels like, so I have nothing to compare to... I just know its quite a bit faster than my '84 Firebird w/160 Hp V8 LG4... [img]graemlins/toto.gif[/img]

[ January 27, 2003: Message edited by: ChillPhatCat ]</p>

[nikkev]

Hmmm,I don't know what the problem is but there's definately a problem.My A4 Z28 gets around 29mpg on the highway.
Kevin

[Dominic]

Had you driven into a headwind or done a considerable amount of passing your fuel economy would drop. I never get fuel economy that low on the highway, but don't use one trip as your estimate.

Try taking it out for a 100 mile cruise down the interstate this weekend and check it, it might not be so bad... Also fuel pumps can be inaccurate as well, so try to use the same one if you're trying to be accurate.

[Scott Myles]

I have a 2000 M5 and get similar gas mileage...in fact, I've never gotten better than about 24 MPG. I have noticed that the mileage seems to be getting a little better as I get a few more miles on the car though.

[00swartz]

Traveling west across the state into the wind, I still averge over 27-31MPG with an 3.8/A4. Something is not right.
To be accurate, eliminate the variables and fill at the same place each time so you get a consistent amount..Do that two or three times and then try another vendor..your milage may vary considerably.

[navyblue2000]

looks like you're from new york...
i think we might have the same problem...colder air = more dense = more air = more fuel. Given some 'winter mixes' gas companies may use, ,that might be your problem

[ChillPhatCat]

I agree, it may be the winter gas mix, it may be the snow tires... I will wait til summer to see what really is going on... mileage isn't a factor though, I have 97k on the clock... I was hoping for slightly above average mileage with the headers... we'll see.

[Everglades W68]

I think you should be getting better mileage on highway. Snow tires may really drop mileage.

[WickEdSix9838]

that is bad cuz i got 27.55 the other day and i have 3.73's!!!

[99Camaro99]

I get around 19-20 when I 30% highway 70% city

I get around 22-23mpg when I do 50%/50%

On a highway trip with a lot of flooring it with 118 runs I got about 25-26mpg. Hope that helps.

Oh and your LS1 power question. Just think of this

Stat You / LS1
0-60 7.4 / 5.2
0-100 22.1 / 13.0

:D

[W68Firebird97]

I was avg. about 24 or so give or take and depending on my foot also. But last year when I went to Virginia Beach,VA to meet up w/ the Coastal V6ers I went 34 miles to the gallon [img]graemlins/omg.gif[/img] I couldnt believe it. And yes I calulated it 3 times to make sure I wasnt messin up. And I drove from southern NJ and went down RT 1 which is so flat you could see about 6 miles ahead and driving straight. But that only happened once and like I said before I avg about 24 mpg.

[CamaroBill]

Maybe you got a car with gears? (3.73s)

Would definitely make the car quicker than a stock V6 (still a far cry from LS1 territory) with a mileage penalty.

My V6 M5 3.8 w/bolt-ons and 3.23s got 30 mpg even all highway. Now with the 3.73s I get only 23 on the highway albeit with much better "punch".

[ChillPhatCat]

Is there a code stamped on the differential that would tell me what ratio I have? If there is I could at least check to see if it is or isn't a 3.23. I know the RPO code is GT4... which is not what I had stock... GU5 is on my RPO sheet which is 3.23.

I was also thinking maybe the O2 sensor is going bad or the catalytic converter... I'm not getting a loss in power though... would the engine light always go on for those?

[ January 30, 2003: Message edited by: ChillPhatCat ]</p>

[99firebirdconv.]

I get 22 city with my a4, and the best ive gotten is 32 mpg on the highway. Recently though cuz of the cold im not getting as good gas milage. :D

[UNFNick2k]

I gotta 2000 bird Y87 with a 5 speed, mods include holley filter and whisper lid as well as B&B triflow catback. The engine has only run Mobil 1 synthetic and I'm getting about 34mpg on the highway at 75mph with the cruise control on, running at approx 2k rpms...