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Hey guys I am trying to get the best gas Gas mileage out of my 98 lesabre with 253kms.
I do fuel filters every 25K just did my air filter and did a full tune up spark plugs + wires just replaced the front O2's sensor (ac delco) still have the one in the cat to replace, pcv valve just replaced too. I only get a little under 400kms to a tank, a lot of my driving is in town and I have a gutted air box, is there anything else I am missing to bring up to par to help get me some more Mpg? ive changed my driving style alot too im driving MUCH more like grandpa these days. anyhelp is wanted and much appreciated. Thanks again.

The post-cat O2 sensor has no effect on performance or fuel mileage. A stock L36 should get 28-30mpg in SUMMER maybe a couple lower in winter.

That 28-30 won't be around town. The definition is pretty loose also, things differ greatly in a more rural Ontario, compared to around town in the Toronto area. Where are you located, rogers9c1?

It's really hard to say if 400kms per tank is normal, we need proper calculations to say how much you're really using. How many litres are you putting in per 400km? With city driving in and around the Greater Toronto Area I'm looking at about a 50L fill for 400km: 12.5L/100km, 18.8 mpg US, or 22.5 mpg imperial. Your LeSabre will not be too far off, I would estimate 10-15% better.

I manage 27 mpg driving up/down hills at high speeds. 400 miles a tank.

When I delivered pizzas, I got 17-18 mpg since it was all accelerating/stopping/idling. ~250 miles a tank. Not locking the TCC on these cars kills the fuel mileage quickly.

I've only had my '95 Bonneville for a little over a week, so I haven't yet had the opportunity to calculate mileage. My '97 Olds LSS would do in the upper 20s on the highway and 16-18 around town. The best I ever got was 34 between St. Augustine, Fla. and Columbia, S.C. on a warm New Year's day.

I drive practically all highway, and I get between 22.5 and 23.5 MPG. I got 26 MPG on the way to WCBF in 2008. Part of it depends on your final drive ratio. Mine will give the worst gas mileage.

Your 400 Km on a tank is around 250 miles. I regularly go over 300 miles on a tank, which would be 480 Km. Have you checked your plugs recently?

Driving to Cincinnati and back in my brother's 2000 LeSabre a month ago, we Managed 33 mpg on the way out, and 32 on the way back. He's got old tires, 1 year old plugs/wires, fuel filter in mid life, and a new air filter, i'd call it a average, or slightly tune up. He's got the lower FDR i'm sure of it.

We had a 600 mile range!

Bugsi wrote:I drive practically all highway, and I get between 22.5 and 23.5 MPG. I got 26 MPG on the way to WCBF in 2008. Part of it depends on your final drive ratio. Mine will give the worst gas mileage.

Your 400 Km on a tank is around 250 miles. I regularly go over 300 miles on a tank, which would be 480 Km. Have you checked your plugs recently?

Something is wrong with your car....

I did 28 up and 29 back with my 03 Loaded down( my trip to WV and back to FL )

The 95 Bonneville always did 28-32 depending on my foot to the floor runs...lol

In town the 03 averages 21, the 95 Bonneville averages 22( flat land too ) 03 SLE has a 3.05 ratio, 95 Bonneville has a 3.06 Ratio...


The van is a different story... 16-18 in town, and 23 on the road..... 3.33 gears.... The bumpy cam and the tune do not help me...lol

I've been able to get 37mpg on one-hour highway trips in my 2000 Bonne SLE, by using hyper-mileage techniques (which my son describes as "driving like grandpa"). Around town it drops to 25, due to stop signs and red lights and slow-moving traffic. I'm not a hardcore hyper-miler either -- my car is still stock and I'm not crazy about taking seats out, overinflating tires, and other extreme measures that some hyper-milers take to squeeze out more mileage.

Instead, I focus upon driving technique. I could write a long article on this, but it boils down to this:

1) Slow down. On the highway, I usually drive about 60mph while trying to keep my RPM's around 1800. This is much easier if you can follow a slow-moving vehicle like a truck or something. Otherwise you have to get used to everybody passing you, which tempts you to speed up because you feel silly going so slow in such a sporty car.

2) Increase following distances. A key element of mileage efficiency is to minimize accelerations and braking -- smooth sailing gets the best mileage. If you have a long following distance ahead of you, sometimes a slowdown by the car ahead will be over before you get there, and you can keep going, uninterrupted. Or at least have time to change lanes.

3) Avoid jack-rabbit accelerations. Again, smooth and steady wins the race.

4) Turn off the radio and give driving your undivided attention. I have seen my mileage fall when I start daydreaming, both because I start speeding up and braking more, and also because I fail to notice things going on up ahead, forcing me to brake more often. My mileage, when not paying attention and falling back into old habits, averages 22 City / 27 Hwy.

5) Leave 5-10 minutes earlier than you otherwise would. These techniques are hard to do if you're in a hurry.

For beginners, simply try using your cruise control alot and setting it for lower speeds (like 60mph). You should see improved results almost immediately. Then, after the thrill of that wears off and you crave even better mileage, educate yourself about hyper-mileage techniques via a Google search and enjoy even more savings!

One last thought -- since I started doing this, I stopped getting speeding tickets and my brakes last much longer. So, in addition to fuel savings, these other savings are adding up too.

Ken_W

P.S. I can get 24 city / 29 hwy in my 04 Montana using the same techniques.

I got 24 MPG going from St. Cloud to St. Peter MN on mostly 2-lane backroads this afternoon (If I had originally known I'd be going to St. Peter, I'd have taken freeway, but didn't know till halfway home) which was really good considering the amount of passing and slowing and accelerating I did. I set the cruise at about 63 and let it roll.

repinS answer is the best so far. I get about the same with both my Lesabres, about 20 mpg. Above the 49th parallel our cars are starting quite cold, so we lose mileage as the engine warms up. Stop and go traffic will really hurt your mileage too, as will hills.

On my Grand marquis, with its V8, I could monitor the milage on the digital dash. On the freeway at a steady speed, it could get 30 mpg. As soon as I had to stop in the city, the average would drop to 20 mpg pretty quickly.

I've been getting owned by stop and go traffic since I work in downtown Toronto and drive a couple days a week (the subway gets used an abused the rest of the days).

I've been seeing approx. 16 miles per US gallon, or 14.5 - 15.0L/100km.

26.9 average the past few months, over the summer I got around 24 since it was only around town driving to and from work, no highway. Oh yeah, I also run 89. I've gotten 32 average before on a 400 mile trip. 2000 Impala LS, L36, 3.05 gears, high flow cat, intense pcm, intense fwi

With my foot keeping the Buick's accelerator to the floor, I got 27 mpg hauling a car full of stuff at 72 mph last night. On a longer trip it would have been higher, since it was an hour going mostly uphill.

With these cars, it's all about driving technique. Driving gently on the highway will yield better results than driving like a maniac.

I think the MPG may also vary depending on what gas you are running.....

I'm running '87 Octane. My most recent tank of gas just got me 23.31 MPG (most of it was freeway miles). This is the first tank I've ran with the L67 coils on my N/A 3800 (and it appears this was a 1 MPG gain compared to the last time I checked my MPG when I put a ZZP downpipe with high flow cat on the car earlier in the year).

I won't be able to get anymore MPG info until next spring (the car has been parked with the winter).

The only way a higher octane will get you better mileage is if you have KR with lower-octane fuels to begin with. There is no more 'power' in a gallon of 92-octane fuel than there is in 87-octane.

The LeSabre gets about 29mpg (unmodified except for 180 thermostat).
The SLEeper gets about 30-31 on the freeway (mildly modded).
The ZiLLA gets 32-33 at 70-75mph on the freeway (over the pass into CA or Eastern Oregon), heavily modified. Around town, it's about 12.

For those that are new to the forum, the SLEeper and ZiLLA are both supercharged.

willwren wrote:The only way a higher octane will get you better mileage is if you have KR with lower-octane fuels to begin with. There is no more 'power' in a gallon of 92-octane fuel than there is in 87-octane.

And this is exactly the reason I'm using it, Todd suggested I try it out after KR spiked a few times and I found it runs much better with higher octane

I got 33.8 mpg once in my Buick.

Most of the time though on the highway it was in the upper 20s. Around town anywhere between 16-18.
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repinS wrote:That 28-30 won't be around town. The definition is pretty loose also, things differ greatly in a more rural Ontario, compared to around town in the Toronto area. Where are you located, rogers9c1?

It's really hard to say if 400kms per tank is normal, we need proper calculations to say how much you're really using. How many litres are you putting in per 400km? With city driving in and around the Greater Toronto Area I'm looking at about a 50L fill for 400km: 12.5L/100km, 18.8 mpg US, or 22.5 mpg imperial. Your LeSabre will not be too far off, I would estimate 10-15% better.

Sorry for the long delay in replying Been busy with work. I am located Kitchener Ontario. Tonight I am going to fill my tank from the half way mark reset the trip switch, and see what I get doing just the speed limit and very light foot action, trying to keep the car under the 2000rpm mark. I don't really like running the car under the half way mark as I have a fear of running out of gas but I should be OK for the week. Thanks for the tips so far I have put a few to use. One thing i did want to know is that I do get a cel for p0442 every now and then and I some times smell raw fuel on cold starts? maybe related? egr have any effect on gas mileage? and are you guys running a scan gauge to get your MPG numbers?

Since you're filled up now and reset the trip, when you get gas next just fill till full again, see how many gallons you put in, then divide whats on the trip by how many gallons you put in. Easiest/most accurate way IMO.