3.8 gas mileage & ?????

[Redcarguy]

I'm thinking of adding a 98 + Firebird V-6 to my stable, can anybody give "real world" fuel mileage ratings on it? There is no way I want to drive my LS-1 cars on a daily basis and my balloon note is going to come due so I want to plan ahead. Also what is the life span of the 3.8 engine before a rebuild is required? Remember, I am only interested in the 98+ cars so the 3.4's do not really concern me, also it has to be an automatic. I also do plan on racing the car so how do mods effect the fuel mileage??

[Nachius]

96 3.8 auto
3.42 gears
intake
exhaust (full headers back)

Averaged 31 MPG highway

[BobbyZ72]

97, 3.8, auto, 105K, mint condition, all stock.....highway, w/ac, 70mph, very very few stops, about 25 mgp. every once in a while ill get 27, one time i got 37, i must have got some good gas, has never happend again.

[NOS2006]

I'll pu tmine in here in a few days when I fill up.

I'm trying real hard to keep acceleration minimal and leave the SGS function on so I keep the RPMs down a bit lower to start. I've got over 130 miles and I'm a little past half tank.

Oh, and I've got intake and exhaust done. Stock 3.08 gears.

[NOS2006]

Also, simply put, the better the car breathes, the better the gas mileage you'll get. Better intake and exhaust flow help the mileage; higher gear ratios hurt it.

[BobbyZ72]

just fill up now, 130 divided by the gallons you put in. Normal on a tank i drive no more the 180 miles till i fill up, just like to always have planty of gas, you never know what could happen over night. As for how long these cars last... i know 2 people with over 250k and still going strong.

[PewterBird]

Im probably the worst case senario when it comes to gas mileage.

275/40/17 tires all around
3.42 Gears
2800 Stall speed torque converter
97,000 miles

and Socal Traffic

16-17 City about 22 highway.

[Need4Camaro]

Originally posted by Redcarguy:
I'm thinking of adding a 98 + Firebird V-6 to my stable, can anybody give "real world" fuel mileage ratings on it? There is no way I want to drive my LS-1 cars on a daily basis and my balloon note is going to come due so I want to plan ahead. Also what is the life span of the 3.8 engine before a rebuild is required? Remember, I am only interested in the 98+ cars so the 3.4's do not really concern me, also it has to be an automatic. I also do plan on racing the car so how do mods effect the fuel mileage??

Before I state my old 3.8's MPG I'll have to say I drive an LS1 and the MPG difference is almost null and void... I'm easily getting 30 MPG at 75 - 80 MPH... 400 miles to a tank when even my 3.8 V6 couldn't perform that at THOSE speeds... However we typically get horrible MPG at lower speeds my worst being 21 at mostly 45 MPH...


As for the 3.8 however... Intake, 3.42's and was getting about 25 MPG all the way around. It was more consistant about fuel milage than my LS1 is I'll have to give it that. As far as lastability? I believe they're well capable of exceeding 300K miles with proper maintaince... Just don't be too late on oilchanges and watch the rearmain seal...

[mjparme]

I'm trying real hard to keep acceleration minimal and leave the SGS function on so I keep the RPMs down a bit lower to start. I've got over 130 miles and I'm a little past half tank.

You do realize SGS really hurts your gas mileage right?

I have a 99 auto, with 3.42 gears, I get 17 city and 26 interstate (at 75 mph).

Honestly, if your LS1 is a six speed it probably gets better highway mileage than the V6.

The 3.8L is a very reliable motor. However, like any motor maintenance plays a key part in longevity.

[BobbyZ72]

well crap, i wish someone would have told me the v8 got about the same gas milage on the highway., but i guess i didnt ask. i would have considered it when i was shopping for a car. My silverado with has the 5.7 engine gets terriable gas milage about 14 hwy, thats why i got the v6.

[Fred]

I own a 2000 v6 firebird auto and a 2000 trans am auto. With the firebird I get about 20mpg and in the t/a about 18mpg. Both have headers and the cold air kit. I love driving both of them. If you get a v6 make sure you get it with LSD and 3.42's, it makes it more fun to drive. I've got 78,000 miles on the Firebird and haven't had any major problems with it.

[NOS2006]

Originally posted by mjparme:
</font><blockquote>quote:</font><hr /> I'm trying real hard to keep acceleration minimal and leave the SGS function on so I keep the RPMs down a bit lower to start. I've got over 130 miles and I'm a little past half tank.

You do realize SGS really hurts your gas mileage right?</font>[/QUOTE]Wow, no **** it does! I've been using it 24/7 since I filled up last and driving like a grandma. I have a '98 A4 3.8 with 3.08s and only intake/exhaust done. I got 14.86 mpg city. That's terrible!

[NCState98]

^durrr Not to mention the extra wear on your tranny

[NOS2006]

Really? I seriously didn't know it was bad to use.. Damn.

[Flowbee V6]

Its better to go by tank fillups

my tank is 15.5 gallons and a year ago I was able to reach 400 miles before running on fumes with 70hwy/30%city driving.

However, for the last few months my miles to a tank have dropped to around 340+, sometimes under 340. I need to figure out what the culprit is. This is with 96k miles on the odometer

also keep in mind the gas gauge itself can be very misleading and drop to empty when you really have over a gallon left in