Gas mileage

[sepenator]

Well I only get about 15 miles to the gallon, so I was wondering if there was anything besides major upgrades to the engine, that I could do to improve the gas mileage in my 2000 SSEi bonnie.

[harofreak00]

Is that city/highway or a mix?

You can start by staying out of the loud pedal.

AFAIK there aren't any major upgrades that you can do to the engine to get better mpg. Just do a tuneup and you should get 30mpg on the highway no problem.

Brand Suggestions are in the parentheses.

• 1987-2005 Bonneville / Buick 3800 Maintenance List
  
  Run Seafoam through gasoline and intake every 5,000 miles. One pint of Seafoam in a half tank of fuel is a good mix. The intake is optional, but recommended.
  
  Grease: Ball Joints, Tie Rods Every 8-10k ( Green Grease recommended)
  Air Filter Every 15k (Amsoil EaA, Purolator PureONE)
  PCV Valve Every 30k
  MAF Sensor Element Cleaning/TB Cleaning Every 50k viewtopic.php?f=48&t=1661
  Fuel Filter Every 15-25k (Purolator, AC Delco, WIX)
  Spark Plugs Every 30-50k (NGK TR55 or Autolite 605) (Never Bosch)
  Ignition Wires Every 30-50k (Napa Belden, AC Delco, Autolite Pro, NGK) (Never Taylor or Bosch)
  Oil & Filter Every 5-6k or Every 6 months (Mobil1 or Amsoil)(Mobil1, Purolator PureONE, Amsoil EaO or WIX) (Never Fram) viewtopic.php?f=45&t=214
  *Conventional Oil Every 3k/3 months(Pennzoil with a WIX (Napa), Delco or Purolator filter)
  Transmission Flush or Pan Drop Every 15-20k (Always make sure filter is changed when flushed) http://www.pontiacbonnevilleclub.com/fo ... 45&t=10193
  Cooling System Flush Every 25-50k or 3-5 Years (Peak or Prestone Green Coolant Only) (Never Dexcool)
  Oxygen Sensor Every 80-100k (30k for non-heated) (AC Delco or Denso) (Absolutely never Bosch) viewtopic.php?f=48&t=794
  Accessory Belt Inspect every 15k, replace every 100k, or as needed
  Cabin Air Filter Inspect and Replace every 15k, or as needed in dusty conditions. (Note: 00+ Only)
  Evap Core Cleaning Whenever Needed (Note: 99 and older only) viewtopic.php?f=45&t=2432
  
  *Special Considerations*
  All 3800s, LG3, LN3, L27, L36, L26, L67 & L32, especially important on vehicles factory installed with orange Havoline Dexcool Antifreeze/Coolant: http://www.dex-cool.net/
  Lower Intake Manifold Gasket Replacement, every 80-100k (ignorance of this can allow coolant to enter your engine oil, this happening can cause irreversible lower engine damage, requiring replacement of subject engine)
  
  Series II, Naturally Aspirated, RPO:L36:
  Upper Intake Manifold Plenum Replacement, Every 80-100k (ignorance of this can allow coolant to enter your intake manifold, possible damage to occur can be hydrolock, irreversible damage to emissions devices, misfires, etc. Most times, engine replacement is required if ignored long enough.) viewtopic.php?f=53&t=1061
  
  Series I, II, III RPO Code L67 & L32:
  Change Supercharger Oil; Every 30-50k. (Intense Racing or GM Dealer) viewtopic.php?f=56&t=1690
  Supercharger Belt; Inspect Every 15k, Replace Every 100k or as needed.

[2000Silverbullet]

I have always been able to vary my fuel mieage between 12 mpg and 27 mpg.

So much is dependent on how heavy your throttle foot is, your average speed and how much idling you do.

[redeyesbonnie]

In my 2000 SSEI the highest gas mileage I've seen is 18.2 according the DIC. This is 80 to 90 percent short trip city driving.. IIRC last time i checked it on the aeroforce it said 13 or 14 MPG And i'm not that heavy in the throttle, every once in a while there might be a WOT

[repinS]

I have always been able to vary my fuel mieage between 12 mpg and 27 mpg.

12 and 36 mpg (US gallon), I got you beat Paul

Driving style and ambient temperature seem to go a long way in varying my mileage. The 12 I got was from 100% city driving in below freezing weather, lead-footed with many short trips. The 36 was a 100% highway road trip where I pussyfooted around 60mph in the summer time.

[sepenator]

I do mostly city driving save for a few trips across the city to visit family or something, I'm just trying to gauge if I'm in the average for everyone else or if i need to fix some things with the car, I'm gonna get a fuel filter and wires and the other tune up stuff this weekend, I did and oil filter and oil change and air filter change already about 2 weeks ago and saw a slight increase but it wasn't much.

[harofreak00]

An oil change isn't going to increase mileage.

When oxygen sensors go bad they kill mileage.

However if you are doing mostly city driving, 15 sounds about right. Probably should be closer to 18.

[olblueeyesbonne]

Also depends on your driving style, and what modifications you have done.
With moderate mods (CAI, full exhaust, SC pulley, tuning and maybe some light porting (exhaust manifolds, SC, TB) you will suffer in town, but if your highway miles are over 70% of your mileage then it should even out or even improve overall.

[bonnevillain]

Around town with what I think is a fairly heavy foot, i still get 18. That's with the 3.06 gears too.

[00Beast]

Ryan, you're also N/A. Big difference.

Oil change, plugs, fuel filter won't increase fuel mileage per-say, but it will bring it back to where it should be. I heavily recommend replacing your front O2 sensor. I replaced mine this weekend and wish I'd have done it when I got the car.

[bonnevillain]

D'oh! didn't realize he was supercharged. As already mentioned, the 02 sensor is often the culprit in bad mileage, i'd look there first. After that, plugs.

[2000Silverbullet]

12 and 36 mpg (US gallon), I got you beat Paul

The best I have ever managed over a full tank of fuel and 600 km is 27 mpg but I have gone for short highway distances and seen 36 too.

My biggest problem is I can't drive 55. 70 is average but lately on this wonderful Island highway it's been 100!
Miles an hour. I'm embarrassed to say the last time I was following a Vibe. Now that just kills mileage.

[LeSabre in Buffalo]

15 and 39 mpg. 100% city and 100% I-95 for 600 miles on ~15.2 gallons.

Front O2 sensor will have an effect. Also, running a good fuel system cleaner like Chevron Techron Concentrate or Gumout with Regane will help.

[Bonneville'n]

Thought I had a problem to, but I average 17-18 mix and Im heavy with the right foot. My best all hwy was 26ish Guess Im normal

Bought it to mat it!!

[94SilverSSEi]

I have been averaging anywhere from 13-15 and I am N/A
I think the crappy winter gas blend has had a big affect but we'll see this summer

[golfyeti]

I have been averaging anywhere from 13-15 and I am N/A
I think the crappy winter gas blend has had a big affect but we'll see this summer

There are a number of things tied to winter that affect gas mileage. Longer warm ups, tire slippage, slower/longer city rides due to slippery conditions, etc. Even my big nubby winter tires took off about 8-10% on my hwy mileage this winter.

With summer tires on I get about 17 city // 29 hwy @ 70-mph, and have seen 33-34 at 55 mph.

[LeSabre in Buffalo]

Warmup time is huge. It takes ~10-12 minutes to fully warm up the coolant at 30 degrees F. That's energy that's going into the coolant, not into moving your car down the road. In 90 degree F heat my car warms up in less than 5 minutes. That's 5 more minutes of going instead of warming up the car.