I recently purchased my used car, why is my car so bad on gas

65

Asked by Feb 08, 2007 at 05:18 AM about the 1998 Pontiac Bonneville 4 Dr SSEi Supercharged Sedan

Question type: Maintenance & Repair

16 Answers

17,805

Hello, There may be a number of reasons for this. First, Bonnevilles are not the best on gas. They average 22mpg on combined city and highway, according to fueleconomy.gov. Next, it's an older car, so the other owners may not have taken great care of it. I would recommend getting a tune-up. If you can't do that, then fill your tank with high-octane gas to clear out the lines. I hope this helps! CarGrrl

1 of 1 people found this helpful.
Best Answer
195

Well what is your definition of bad on gas? You should get about 18-22 in the city depending on your driving style, i get about 20, and you should get about 26-29 on the highway, I get about 27.

2 of 2 people found this helpful.
10,235

very important that you use premium fuel. The computer retards the timing if it detects premature detonation that is caused by using regular unleaded in a supercharged engine. I owned a gtp with the same engine and averaged 18-20 around town. The Bonneville is a heavier car so I would expect closer to 18. I used regular unleded gas in my gtp once by accident (wife put gas in), and I got about 8 miles to the gallon.

35

Yeah, idk if you have the manual with it, but the SE takes regular and the SSEi requires 91octane or higher...

385

Cause its a big s'charged V8. What did you expect?

1 of 1 people found this helpful.
45

tune up and keep your foot out of it

2 of 2 people found this helpful.

it's a v6, and should get 25 mpg (I have the same engine in a 97 grand prix)

385

Ha, my assumption about american cars with V8's overtook my willingness to think before i speak

670

using regular gas in it? that will make the computer go nutty when that big ass supercharger winds up try using premium or getting a car that isnt a supercharged v8

35

1. its supercharged 2.its a V8 3.its supercharged. u gotta use premium gas too. using regular on a supercharged or turbocharged car can decrease mpg..

55

Another thing you may want to try is a K and N air filter. I put one in my Jeep Liberty and with a fresh oil change, I noticed a significant change in gas mileage.

245

If you are using your a/c it will rob your gas mileage also.

35

Swap a turbo on and keep out of boost should solve half of the problem..........but the pricing? i dunno.......

25

because its a piece of garbage.

I have a 2001 Bonneville supercharged and you can simply have it running for a split second and the Overflow container boil what could cause that

Phantom1213, are you sure it is boiling or are you getting bubbling from a blown head gasket?. It's really impossible for an engine to over heat that fast. Here is a bit of info about nearly every 3800 liter V6 ever built since about the mid 90's. The factory failed to do a proper job of engineering the front exhaust manifold on these engines. Number 5 cyl. is subjected to excess heat from back pressure on account of this issue. The head can crack between the valve seats and also you can loose seal of the head gasket from the heat. In the most serious cases these engines will stick the piston in the cyl. and cause it to break which will completely destroy the engine block ! The best way to address this problem is by installing what is referred to as a power log manifold made by a company called ZZPerformance. It eliminates the back pressure on number 5 cyl, if and only you have taken care of the problem of compression leaks into the radiator if this is what is causing the over flow tank to bubble over.

Your Answer

Add photo

Related Questions

Bonneville

Looking for a Used Bonneville in your area?

CarGurus has 511 nationwide Bonneville listings starting at $1,799.

ZIP:

Search Pontiac Bonneville Questions

Pontiac Bonneville Experts

#1 ticklemedaly
ticklemedaly
Reputation 380
#2 Js08016
Js08016
Reputation 360
#2 dandyoun
dandyoun
Reputation 360
View All

Related Models For Sale

Used Pontiac Grand Prix
30 Great Deals out of 2,863 listings starting at $1,600
Used Chevrolet Monte Carlo
20 Great Deals out of 1,419 listings starting at $1,995
Used Chevrolet Camaro
245 Great Deals out of 31,195 listings starting at $369
Used Pontiac Firebird
4 Great Deals out of 768 listings starting at $1,791
Used Chevrolet Malibu
1,065 Great Deals out of 77,909 listings starting at $1,500
Used Pontiac Grand Am
1,183 listings starting at $1,599
Used Buick LeSabre
19 Great Deals out of 1,919 listings starting at $1,000
Used Ford Mustang
537 Great Deals out of 45,845 listings starting at $1,999
Used Buick Regal
131 Great Deals out of 11,078 listings starting at $2,999

Used Cars For Sale

2005 Pontiac Bonneville For Sale
83 listings starting at $3,495
2004 Pontiac Bonneville For Sale
3 Great Deals out of 66 listings starting at $1,799

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.