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DBeaSSt

Real world MPG?

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I know there are a few of you who have one of the 3800 engines in your cars. What kind of real world fuel mileage are you seeing? Highway and city?

I'm pondering a Riviera as there are a couple decent ones available locally.

Also, am I correct in thinking that the mid/late 90's 3800 suffered the infamous intake(?) gasket failure problem which the 3100's suffered?

TIA!

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My parents had an '88 Olds delta 88 with a 3.8 that got 30-31 on the highway.

I had a '03 Impala with a 3.8 that got ~24 city and 32 Highway (65mph and under) and 28-30 above 75. The Impala got better milage than my new Malibu with the 3.6. With CAFE, maybe GM will have to revive the 3.8...

Neither of these motors ever had any trouble.

Edited by biff
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My parents had an '88 Olds delta 88 with a 3.8 that got 30-31 on the highway.

I had a '03 Impala with a 3.8 that got ~24 city and 32 Highway (65mph and under) and 28-30 above 75. The Impala got better milage than my new Malibu with the 3.6. With CAFE, maybe GM will have to revive the 3.8...

Neither of these motors ever had any trouble.

3.8 is dead. Lower mileage in the 3.6 is due to a combination of weight and transmission pairings.

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My 2003 Grand Prix GT, had a 3800 engine in it. We took it to Maine a few times from Delaware and we averaged about 32 mpg on the interstate.

On a side note, we went to the Lobster Fest in Rockland, ME, I could not figure out why there was so much traffic in Maine when I got there, every lane on I-95 was packed. I later learned that the next day, the Lobster Fest started, along with one of the last Phish concerts and a week long Lesbian convention. :spin:

Edited by Pontiac Custom-S
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3.8 is dead. Lower mileage in the 3.6 is due to a combination of weight and transmission pairings.

Ya I know, I didn't have a sarcasm smiley. The 6 speed really stretches the legs on the highway and is geared down in town. Only has 5k on it tho, and keeps getting better.

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Thanks for the feedback guys! I was hoping I'd be able to see a 25-6mpg average in one. Looks like it'll be right about on with the numbers you've posted.

So the 3800 doesn't have the gasket failure problems of the 3100?

Mike

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Yes it has the plenum intake gasket... but you can get that plenum gasket replaced with an aftermarket one that won't fail like that... the parts are out there... if you are concerned.

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Yes it has the plenum intake gasket... but you can get that plenum gasket replaced with an aftermarket one that won't fail like that... the parts are out there... if you are concerned.

I was thinking that...But most of the 3.8 are fine from what I have seen.... :yes:

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jDepends on the vehicle:

I bet if you shoehorned a 3800SC into a Yamaha crotch rocket it would get

25-40 MPG but on the other hand a 3800 NA powering a breadtruck full of

lead bricks at 80mph with a poweglide would get about 4-7 MPG.

Hope that helps. ;)

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My mother-in-law had a '95 Riviera with the SC 3800. We took it on several trips and I had no problems averaging 30+ MPG on the highway. I normally kept speeds in the 65-70 MPH range.

Back in 2006, she traded the Riv for a Volvo S60 non-turbo with an auto tranny (2.4L inline five). It has yet to achieve the highway MPG of her old Riv. and the Riv had a smoother and much quieter ride to boot.

I was an idiot for not buying that Riv before she traded it; what a great car.

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3.8 is dead. Lower mileage in the 3.6 is due to a combination of weight and transmission pairings.

My parents have a 2000 Regal GS SC.....and my dad has always complained about the mileage....but then again he has a '99 Vette 6-speed that he drives (the Regal is a 3rd car for them) and he doesn't really get that much better mileage in the Regal....and feels he should since the Vette has ~ 350hp.....

I think they get around the low-20's for the GS from what he's said. That's about what he gets with the Vette.

I will say this.....their car has like 150K miles on it....and that powertrain is FLAWLESS. I don't know that they've EVER had a problem with the engine OR transmission. The REST of the car, however, is a travesty.......and my Dad is Mr. Anal when it comes to taking care of and cleaning cars.

The Regal has really loosened up so dramatically......plastic pieces don't stay on, knobs and switches fall off or don't work......the suspension creaks and groans so much it's embarassing.

The overall powertrain reliability of their car has been steller......but after 100K miles, you can tell that these cars were built to a price when it comes to non-powertrain-related issues......I really think that's where the domestics get a bad rap. They simply don't do well after 80K miles or so.......(again...powertrains aside.)

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My parents have a 2000 Regal GS SC.....and my dad has always complained about the mileage....but then again he has a '99 Vette 6-speed that he drives (the Regal is a 3rd car for them) and he doesn't really get that much better mileage in the Regal....and feels he should since the Vette has ~ 350hp.....

I think they get around the low-20's for the GS from what he's said. That's about what he gets with the Vette.

I will say this.....their car has like 150K miles on it....and that powertrain is FLAWLESS. I don't know that they've EVER had a problem with the engine OR transmission. The REST of the car, however, is a travesty.......and my Dad is Mr. Anal when it comes to taking care of and cleaning cars.

The Regal has really loosened up so dramatically......plastic pieces don't stay on, knobs and switches fall off or don't work......the suspension creaks and groans so much it's embarassing.

The overall powertrain reliability of their car has been steller......but after 100K miles, you can tell that these cars were built to a price when it comes to non-powertrain-related issues......I really think that's where the domestics get a bad rap. They simply don't do well after 80K miles or so.......(again...powertrains aside.)

I could say the same thing about my neighbors Century...man does it make noise...

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'01 Impala LS 9C1 averages about 27 combined city and highway. Strickly highway, she'll easily see 32-35mpg, and in the city I normally se 22-26.

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I had a 2000 Grand Prix GTP 2-door with the S/C 3.8. In the city going by the computer, it got 23mpg, hwy 31mpg running 75mph plus.

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father in laws 08 grand prix doesn't get near the mpg his 98 88 got. the 88 would see 30-33 hwy. the grand prix maybe 26-28.

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father in laws 08 grand prix doesn't get near the mpg his 98 88 got. the 88 would see 30-33 hwy. the grand prix maybe 26-28.

Wonder if it was gearing....

Mom's 94 Bonneville would get that same 33mpg highway.

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Well in my Riviera I have a Series I Supercharged and I get horrible gas mileage, usually between 15-20 MPG in mixed driving and thats even after a engine and tranny rebuild. Not I don't drive it like I stole it either.

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I know there are a few of you who have one of the 3800 engines in your cars. What kind of real world fuel mileage are you seeing? Highway and city?

I'm pondering a Riviera as there are a couple decent ones available locally.

Also, am I correct in thinking that the mid/late 90's 3800 suffered the infamous intake(?) gasket failure problem which the 3100's suffered?

TIA!

I have an 04 Grand Prix with the Series III 3800. Around town (if I drive somewhat conservatively) I normally get 20-22. If I drive it hard, I've gotten as low as 16, but I was really really hard on that tank! On the highway, the best I've ever gotten is just over 30 (30.2). That is with the cruise set at 74, going through some mountains in PA.

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