Gas Mileage

I am averaging between 13-14 mpg (13.6 last time I calculated on an average of 26mph). I do a mix of highway/city driving (depends on the day but the computer tells me my average overall speed is usually 25-35mph). Considering I just changed plugs, wires, fuel filter, air filter, and never really leave the car idiling, I was curious to see what others were getting with their 3.8 and if there is anything else that could possibly improve the mileage-I know it's not great but it's somewhat of a relief nowadays considering I just got rid of a 5.0 explorer with awd that got 7 mpg.
As always any replies are appreciated-
Tim

mine sucks like shit too.

90% highway, and I get about 16 or so. 20/30 my ass.

Yea, I have a 2000 w/ 100k on it- I was wondering if either of those factors played a role considering you would think a lighter car like this would be getting better mileage-I know someone with an early 90's lincoln town car that gets an average of 18 on highway and that things gotta have about at least half a ton and another 6 ft. on the impala. -Oh well

well mine is an 02 with about 60K on it.

And they are by no means light, 3400lbs aint light. but I guess compared to your old explorer, it probably seems light.

Yea, it's my daily driver and I'm still getting used to it-big difference in many aspects-but that's comparing apples and oranges-at least I'm saving half of what I would be paying for gas-Tim

I am averaging between 13-14 mpg (13.6 last time I calculated on an average of 26mph). I do a mix of highway/city driving (depends on the day but the computer tells me my average overall speed is usually 25-35mph). Considering I just changed plugs, wires, fuel filter, air filter, and never really leave the car idiling, I was curious to see what others were getting with their 3.8 and if there is anything else that could possibly improve the mileage-I know it's not great but it's somewhat of a relief nowadays considering I just got rid of a 5.0 explorer with awd that got 7 mpg.
As always any replies are appreciated-
Tim
The Poll is interesting, would like to see the same type poll for the 3400 engine. I know my 3400 mileage is poor compaired to what I have read hear in this forum. 02 63k 16mpg 100% city...but I also don't drive more than 6 mi at a time mostly and figure that is why..New plugs and wires Air filter (standard AC) I also can't see how a fuel filter if it needs changed would effect mileage, but performance yes if starving for fuel. If you can give me reason to change filter and why it would effect mileage I'm listening. Isn't fuel pressure more the consideration?

you should get an average of 25 mpg... more or less depending on the city/highway ratio....but one hting is if your catalytic converter is clogged such as mine was on my monte it will kill your mileage, doeg your car pull as hard as it used to?

I have exellent low end umph! it's 50 on up that seems like I have to floor it to get an aggressive acceleration. figured that was due to the type tranny programming. Haven't gone to the dealer for the cat check, I don't want to pay for it if it's OK. If I remember right it was 70 bucks last fall. Like I said I don't drive very far and get very little highway travel. will be making a 400 mile trip in a few weeks and I'll do a check then. I'll post what I get.

we have a 02 impala with a 3.4 in it and am getting 33 miles pet canadian gal
it is great

Wow, just wow. I'm amazed at the low numbers for some of you guys. I have a full size silverado and get about 18 to 19 mpg. I think my brother in law said he gets about 25 with his 04 impala, but I'm now sure which engine it is.

We have 2005 with the 3.4 and 35,000+ miles. We consistantly get 30.5 hwy and 25-26 city.

I get approximately 24mpg on my '01 with the 3.8L... That's if the onboard computer is correct...

I get approximately 24mpg on my '01 with the 3.8L... That's if the onboard computer is correct...

It's not, its just an estimate.

next time you fill up your gas tank, clear your tripometer, then drive until you fill up next. At the gas station, check your tripmeter, then divide that number, by the number of gallons it took you to fill up. that is your MPG

Example:

300 miles on the tank, filled up 15 gallons at refill.

300/15=20 mpg.

I have a 01 ls 3.8 with 175k miles.I get 25mpg average all the time.While running the AC i get about 22 mpg average.

Is the 175k on the original engine? I'm also guessing that the tranny had to be rebuilt,just out of curiosity how long did the original one last you? The one that I purchased went to about 90k but it also started out as a lease vehicle in Jersey so I imagine that took a toll.

Tim

The Poll is interesting, would like to see the same type poll for the 3400 engine. I know my 3400 mileage is poor compaired to what I have read hear in this forum. 02 63k 16mpg 100% city...but I also don't drive more than 6 mi at a time mostly and figure that is why..New plugs and wires Air filter (standard AC) I also can't see how a fuel filter if it needs changed would effect mileage, but performance yes if starving for fuel. If you can give me reason to change filter and why it would effect mileage I'm listening. Isn't fuel pressure more the consideration?
Finally got that 330 mile trip in...98% highway and mileage was 34 MPG on the nose...just where I was hoping it would be. Very good for this size car in my opinion...I have concluded that short in-town trips cuts that down considerably so I am relieved that I do not have any problems concerning fuel system...2002 IMP 3400 63500mi. Checked twice, 165 mi each way..

Anyone know if there is something that could both be causing my poor gas mpg(13-14) and at the same time affecting the ac?- (it's better than nothing but the air never gets that cool even durring highway driving).

Tim

Anyone know if there is something that could both be causing my poor gas mpg(13-14) and at the same time affecting the ac?- (it's better than nothing but the air never gets that cool even durring highway driving).

Tim
A little more info would help ie: mileage, year, 3400, 3800, recent tune up info if any, and against what type of temps are talking 80, 90+...Off hand there could be a leak in air sys or low on R134 refrigerant or perhaps improperly charged...compressor could be dragging or bound up. for the mileage though I would look at plugs and wires first...

2000ls/3800/100k miles/recent tune up -new wires,plugs,changed air filter,fuel filter,and complete radiator/coolant flush, temps anywhere from 70 on up.
I appreciate the response but I'm guessing this may be a rather costly fix. I mean the gas mileage issue in particular-for a car like this I should be getting more than 13-14mpg even if it is alot of city.

Tim

2000ls/3800/100k miles/recent tune up -new wires,plugs,changed air filter,fuel filter,and complete radiator/coolant flush, temps anywhere from 70 on up.
I appreciate the response but I'm guessing this may be a rather costly fix. I mean the gas mileage issue in particular-for a car like this I should be getting more than 13-14mpg even if it is alot of city.

Tim
Well you may not be as far off the norm as you think, I have the 3400 new plugs, wires, etc. and I was getting 13.5-16 but very little highway 20% or so. As mentioned above I just did a 330 mile round trip and got 34 MPG 98 % highway...if both were 50/50 highway/city thinking around 23-24MPG would be the case. Only thing you can do to be sure is do a long highway only test of say 50 to 100 miles for your own comfort before you spend good money going after a solution you don't need. Those are my thoughts....dave

As far as the ac goes, I used a meat thermometer, the digital kind, and placed in the various ac vents while it was on full blast, I was receiving a readout of 57deg. while driving at varous speeds while it would drop down to 55deg. while I was idling. I'm guessing a recharge is in order although supposedly the previous owner had the (cooling unit-?) replaced at the end of last year and there hasn't been more than about 10k put on it since then. Although I can see the new parts I'm not the most mechanically inclined and am not sure exactly what was replaced considering I didn't see any receipts.

Thanks in advance for any responses-
Tim

I would say your a little low on R-134A your temp should be down in the upper 30's to low 40's

I have a 2000LS that has been a great car (125k miles now). However, last summer the gas mileage started to drop slightly. The on board computer had been saying the mileage was 24.5. And this was an average over 100,000 miles. (I had never reset the computer) So this was truly an "average" MPG.

I had the spark plugs changed at 115K, along with the wires, a fuel injector cleaning and fuel filter. Since then my mileage has steadily dropped to 24.1 on the on board computer.

This would not bother me much, but I just checked the mileage on one tank and got 19.3 MPG. I have noticed on long trips (Atlanta - Columbia SC) that I can get nowhere near the mileage I used to get.

I had the fuel pressure regulator changed per the recall that came out awhile back. Before that change the car had to be turned over for several seconds before it would start, and the engine didn't seem to have as much power. Once he regulator was changed, it started quicker, and the power seemed to be back. Now it is taking longer to start again, and the engine does not run as strong. I'm not sure if this is related to the mileage or not.

So where should I begin to look. I have always loved the mileage this car got, but now I can't help but think that something must be wrong. Any ideas??

113K miles on my '00 LS (3800) and I (still) get a faithful 23-24mpg. If it matters, this car has had a steady diet of Mobil1 (since first oil change at 6K miles) and premium fuel. Most recently I've been using Shell V-Power (premium fuel) and I find that morning cold starts are a lot easier. I feel that I've never skimped and I think that it's paying off now with continued good overall performance.

John

Well G! seems as though you have covered about everything in the tune up. Just a couple ot things come to mind, 1. Air filter condition. 2. throttlebody cleaning. Not much of a drop but could be a degradation of fuel quality which would be temporary the way fuel is being moved lately (formulation suspensions) That and the weather being hotter than normal as of late may have some effect. Tire pressures? Air conditioner on more often? Best I can think of...

Have a 2005 3.8, getting between 28-31MPG depending on how much 10% Ethanol I am forced to buy. When I drive up to Minnesota, all gas there has to have Ethanol in it. Came back again last Friday, A/C on all day, 100deg as I rolled into town, averaged 28+ mpg.

That seems to me a very good mileage considering the size the Impala. Plus it does not have the best profile for drag coefficient. There are so many variables in gas mileage ie: jack rabbit starts or just how many start/stops on a run to extra wt. carried like junk in trunk! I think most of us think we're doing more highway than we really are and therefor think our mileage is bad or something is wrong unreasonably. One can only adapt his or her driving habbits so much then you you hit the bottom line. If it's not enough then one has to decide on going to a smaller engined vehicle. As for me, I like the safety factor of a larger car and think the cost of operation is a price well paid.

I finally got a chance to go for a decent amount of nonstop highway driving (approx. 75 miles). The traffic was very light so I was able to maintain a constant speed of 65mph but I was rather dissapointed with my calculation of slightly over 22mpg.
I know people with various ford panther platform vehicles that pull a good 24-25mpg higway and they weigh approx. 800 pds. more.

Well that doesn't sound too good to me, 75 mi. is not a long trial but should be decent as long as the stop an go portion is less than 5%. mileage will drop quickly when you figure in town driving gets you 13-16 mpg...which seems to be about the avg for these Impalas. I know I stated in an earlier post I thought 50/50 city/highway would give around 23-24 but I am rethinking that from what I have been experiencing with my 3400 Imp. On my trips (2) 320 miles each 98% highway got me 34 MPG. I did not use steady speed in any way, 65-80 and yes 85 too! State Patrol had me on the gun but didn't come after me...whew! Now that would make the mileage factor moot for sure.

Yea, I try and keep it under 70mph considering CSP utilizes everything from planes to DOT trucks to perform radar in addition to their countless unmarked vehicles such as Impalas-rather ironic to be pulled over by one of them if the whole point was to measure the mpg in your own.
Now does anyone think I should invest any money in further researching the low mpg, or just accept it as the best this car can get?
Also, does anyone know if there was any signifigant change to the later model Impalas that would improve mileage considering I notice many people with newer models stating much better fuel economy.
Tim

I have a '01 Impala with the 3.8 and about 105k miles. I consistantly get around 29-30 Highway, and 25-30 City. I don't do much city driving, all highway to and from work. I'm actually suprised to see the low numbers. Even running the a/c I get 27 hwy. I certianly hope my gas milage stays where it's at.

That's real good for the 3.8 ltr. I was pretty disappointed in my 3400's 14-16 mpg during the winter but thought maybe had to do with short town trips every couple of days. Found I was right when I finally got a couple of long highway trips in at 34 mpg. I would still be happy if it were 29-30 for this size vehicle when you figure a new Saab 9-3 is rated at 17-30 with a 210 hp. 2.0 turbo four.

Yea, I have a 2000 w/ 100k on it- I was wondering if either of those factors played a role considering you would think a lighter car like this would be getting better mileage-I know someone with an early 90's lincoln town car that gets an average of 18 on highway and that things gotta have about at least half a ton and another 6 ft. on the impala. -Oh well

I also have a 2000 with 100k on it...I was told my EGR Valve was bad and that's why i had such poor gas mileage..maybe something to check into

Hi, My 3.4 had trouble starting w/a warm engine so I put some Bosch Platinum+4 plugs in there and some MSD Ignition wires... The car starts really good now and my gas milage went up noticeably.

A guy from work put those plugs in his sisters Blazer and she reports a 5-7 mpg improvement!!!!!

'99 Lumina LTZ (3.8L) (65K) I've averaged between 21 and 23 doing mostly city with some highway driving. It sure seems like the first quarter of the tank goes by slower than the last 3/4. I get around 100 miles on the first quarter then only around 200 on the last 3/4. CrAzInEsS!

Save on gas and help your car run smoother. Check it out. (link removed by staff)

Don't know why you are advertising a product for saving gas when we do not allow advertising/spam.

Besides where you are going they don't use gas.
Welcome to Banlandia (http://www.automotiveforums.com/vbulletin/showthread.php?t=517725).

Have a nice trip

TS

'99 Lumina LTZ (3.8L) (65K) I've averaged between 21 and 23 doing mostly city with some highway driving. It sure seems like the first quarter of the tank goes by slower than the last 3/4. I get around 100 miles on the first quarter then only around 200 on the last 3/4. CrAzInEsS!
You didn't know? The gas tank is divided into 2 parts, The top 1/4 is used for highway and the bottom 3/4's is used for city....:smokin: This is not an uncommon thinking on your part as it does seem to be that you get better mileage on the first 1/4 used. However the float on the gauge does not register the fuel above the bottom of the float which can be as much as three gallons in some vehicles. So when your gauge starts to register the drop, you have used that portion not measured which includes that which is in the fill tube as well. This can very with fill up, that is why when measuring mileage it is best to use the same pump and same number of fill clicks for accuracy.

I'd say it matters how we are determining mileage.

I've never trusted the Impala (LS) computer display, but it tends to average out around 16-21 in short trip city driving.

Therre are some things that seem to have an impact on this generalization:

Using the AC can cut about 10mpg off that average and make a differerence in the car's throttle response -- the AC compressor really loads the engine especially at low RPM where it spends most of it's time.

I also think the 3.8L has a powerband that starts pretty high (>2500 RPM), but the PCM logic short-shifts the tranny really early (ie: before the engine is making any "useful" torque) to save fuel and keep the RPMs down to save the engine.

Using the overdrive (D on the shifter) helps highway mileage a lot more than city driving -- We usually drive in (3) or (2) around the city because once the tranny shifts into overdrive at around 45mph the RPMs drop to almost idle and braking becomes more difficult (the engine kind of "runs up" on the brakes) and the constant gear hunting becomes a bit annoying. Also, once the tranny is in OD on the highway, you DO have to floor it to make it downshift to get that "passing power" -- and it's very harsh -- try driving in (3).

I think the 2001 Impala is just too heavy for the tune on that V6.

Is the 175k on the original engine? I'm also guessing that the tranny had to be rebuilt,just out of curiosity how long did the original one last you? The one that I purchased went to about 90k but it also started out as a lease vehicle in Jersey so I imagine that took a toll.

Tim I hear a lot of people talk about these engines poorly. i deliver food for a part time job..... 90% city. i always mess with the milage stuff, the better milage the more money i make. mine is a 2000 3800 series II. city driving i manage around 18-19 but i also drive from carbondale ill to north chicago about 5-6 times a year and it is between 420-440 miles and i have made it in one tank. i always try to get higher and higher gas milage every time. i mean i take the trip more than once a month on avereage. my best is 28.1 miles per gallon going 76 Mph no stops. burned a strait tank of gas at 76mph on cruse control. i have had the car since new and it has 140,000 and i have never had any major problems. some electrical things and it needs a quart of oil between oil changes.

Hello Everyone. First post for me:p anyways I have 04 with the 3.8 I get 22-24 city and 30+highway, I don't use the trip computer cause it is off i use the old math method. Last trip i took i went 250 miles one way and i got 33mpg It was all 70mph driving with maybe four stops in the four hours it takes.

I get about 18.3 mpg on my 03 impala 3.4 L,,, with 106 000 miles,,,:banghead:

2001 9C3 3.8, 119,000 km now. 27000 km driven in 10 months, averaged mileage: 9.15 L/100 km (25.6 mile/g). Replacing the regular papaer air filter with a K&N one saves significantly (fuel usage drops from 9.27 L to 9.0 L per 100 km 26.1 mile/g now). 90% hiway driving but 1/4 hwy with traffic jam.

I get about 18.3 mpg on my 03 impala 3.4 L,,, with 106 000 miles,,,:banghead:


IS your parking brake on? J/k I wonder why?

I have a 02 with the 3.8, and it has 120,000k on it. I drive a average of 300 miles a day and get 27MPG. The diffrence between the computer and checking it at the pump is about 1 MPG. My wife and I enjoy the car, We also have a Expedition and a Sable. The Impala is buy far the the most economical and sporty.

wow, you guys must have lead feet. when mine isnt in the shop NOT getting fixed by incompetent dealers, i average 25 mpg in everyday driving. Road trips (as in driving 4-16 hours) i average 34-36 mpg. mileage is all in how you drive it!

I'm surprised to hear that some of you get such shitty mileage. 16mpg sucks ass, especially for an Impala. My 2000 Impala 3.4 with 70k miles on it gets 32 highway and 22-24 city. I'm only a 16 year old driver and I'm not exactly slow. The only explainations that I can think of for such bad mileage are either a poorly maintained car, or bad driving habits.

my '02 gets 22-25 mixed. 16 MPG may be indicative of a failing/plugged catalytic converter, very low air pressure in the tires or numerous other issues resulting from a poorly maintanied vehicle.

Hi everyone. I'm just now starting to post on here although I've been using this site for repairs for almost a year now. Just thought I would let you know that my 2000 Impala LS 3.8 is getting a steady 29.5 MPG during summer months and about 27 during the winter months. I drive 110 miles round trip per day to work and back. I reset my trip odometer every time. Thats the only tool I have since my fuel gauge is extremely inaccurate (like no one else has seen that).

I just traded my '04 Impala LS with the 3800 (it was leased, big mistake), and I was getting an average of about 22 to 25 all the time. I drive about 75 to 80 most of the time on the xway, and about half my time is spent on there. I had 45k on it when I traded it, and I kept mileage since it was new. One guess for your poor mileage might be the ac compressor might be dragging. That could be the reason for the ac not getting cold too. Have that checked out first.

I have Impala -01, with 78 k on it on 3.8 engine. I drive mostly in the city. So, it is usually makes 19-22 in the city and 25 afre that to 29 on highway, if you are on long time trip ( driving more than 2 hours on highway).I never had more that 30 mi per gallon.
So, if we say that 01 has 20- to 30, so my -01 after 6 years shows ok mileage. Or not?

'99 Grand Am 3.4L 140K miles city/hwy= 25+ mpg weird thing is lately it seems to be getting even better....

What do you mean 2com[pressor dragging? By the way, ac compresor a kind of little bit was dragging, I heard that. But what do you mean how it impacts on the milage? ac also doesn't work good. by the waqy; not enough the cold. Or slow warm air comes and cold also slow.
Can you explain how ac compresor works for loq milage oof DRAGGING? Thanks.

The AC compressor is a belt driven pump -- it takes horsepower ro run it -- when you have it on, your engine has less power, so it needs more fuel to do everything it does -- driving with the AC on has the effect of adding (significant) weight -- you should be able to feel the loss in power, and the engine PCM may also raise the engine idle speed and turn electric fans on high speed (=more fuel consumption) to compensate as well.

The AC compressor has a clutch that activates it only when you turn on the AC modes -- that way it doesn't always rob performance.

The alternator/generator is also belt driven, and its parasitic drag on the engine also increases as the electrical load increases -- so amps, subs, fans, AC, DVD players, LCDs, neon lights, HIDs , etc.. increase electrical load and decrease both performance and mileage when they are operating.

my brother had an 03 impala and he was getting 26 miles to the gallon with like 96000 miles...i forgot which engine he had though

Sorry but this poll and thread has been closed.