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Chevrolet Impala Real World MPG



  • deminindeminin Posts: 214
    We've had our 2006 LTZ, with the 3.9L V6 for about 22 months now, and it has been flawless. We recently drove out to Las Vegas from central Missouri, and on the way back I tracked the mileage. I zero'd everything out when we left Las Vegas, and stopped checking at Springfield, Missouri. Running on I-40 and I-44 at 75 to 80 miles per hour with the AC running, I got 30.1 MPG during that 1200 mile stretch. Needless to say, I was impressed. On a daily average, mostly 2 lane country roads, we get between 26 and 28, which for a car of this size still isn't too bad.
  • slvimpalaslvimpala Posts: 14
    i put in that tornado thing and the Fram Air Hog Air filter and boy it makes hell of a Difference i mean b4 i installed em i was getting around 22-25 thats all city and now I'm getting since i put it in was highest 32 and lowest 28 so it may set you back $120 but it will pay for its self in the longer run i will keep all up to date on when i get to working on the Spark Plugs and etc
  • pulgopulgo Posts: 400
    The "tornado" thing is just a scam.
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    I also made the mistake of purchasing a set of "halo" spark plugs that were supposed to increase gas mileage 10%. After initially installing them on my 2000 Impala I started having problems with the car missing when lugging the engine (as in going uphill at low speeds with the AC on, just before the car would downshift). I subsequently replaced the plug wires (which I had not done previously), and in the process found the shafts on several of the plugs that the wires snap onto were loose (they sort of thread onto the ceramic portion of the plugs).

    So the combination of tightening the plug shafts and replacing the wires solved the problem...for about a month. The problem surfaced again yesterday, so I'll drive it for a little while to see if it consistent, and then pull the plug wires and see if those shafts had worked loose again, or if there's something else going on. While beyond that these spark plugs seem to work okay, they've had no impact on my gas mileage at all (positively or negatively). I would have expected an increase had I replaced them originally with standard plugs, so I was disappointed that I saw no increase with the new plugs.

    If I find the shafts are loose again I'll tighten them again, but if the problem continues to come up I'm yanking them out and will probably put a set of Bosch plugs in there and not worry about it again.
  • I just started driving this car to work everyday. It was my wifes car but she now drives the SAAB 95. My plan is to start documenting the MPG as I try different ideas to improve it.

    So far I have only adjusted the tire pressure to 44 psi (This is the max for the stock tires). My daily drive is from Ortonville, Mi to Detroit, MI (RenCen). This takes me on county roads and I75 (Parking lot).

    I am just starting the log which I will base all of my future results on. The results to date are using the on board computer.

    Drove from Ortonville, Mi to Frankenmuth, MI., I75 with the cruise set on 72 MPH with the A/C on. We had 2 adults and one 4 year old in the car. We averaged 36 MPG on the way there and 33 MPG on the way back (Ran into construction backups on a Sunday afternoon heading south).

    The week of 7 August driving to work and back home averaged 26 MPG. This was combined county Road driving and I75 (Rush hour traffic).

    Today (13 Aug 07) I drove in at 8 AM (Much less traffic). I reset the on board computer after entering I75 (Great Lakes Crossing Exit). Set the cruise on 74 MPH, without A/C and one adult in the car. The traffic was so light I was able to maintain a constant speed all the way downtown. As I exited I75 onto I375 (detroit) the on board computer indicated 40.4 MPG.

    Future improvements:
    Replacing the stock air filter with a new K&N filter. On order, waiting for delivery.
    On the next oil change I will be using Mobile Full Sytn 5-30
    Replacing the spark plugs with Bosch Iridium Fusion plugs.
    Replacing the stock tires with ones that can hadle at least 45 PSI.

    I plan to do each one on seperate tanks of gas and measure the entire tank along with the on board computer for results.

    I am very interested in your comments and suggestions. I have played around with small onboard hydrogen units in the past with good results. This unit may find a place in this effort as well.

  • pulgopulgo Posts: 400
    To measure your gas consumption I would not rely on the computer.

    Just fill up, reset the trip meter to zero.

    Next time, do the same again and divide the gallons printed on your receipt by the miles shown on the trip meter. Reset trip meter.

    Repeat this procedure for at least 3 tankfuls and you will have a fairly accurate MPG figure.
  • quietproquietpro Posts: 702
    If you want to be sure of your consistency, fill up at the same station using the same pump to eliminate calibration errors at the pump. There have been many reports (at least in my area) of pumps that have been intentionally tampered with to overstate the amount of fuel pumped.
  • levellevel Posts: 29
    City driving in Atlanta:

    I consistently got 23.9-24.1 MPG during winter.

    During summer with a/c consistently get 23.2-23.3 MPG.

    Better on hwy, add 2.0 MPG to winter and summer city average.

    This is very good to me. What do you get?
  • steve333steve333 Posts: 201
    2006 Chevy Impala with 3.5L V6
    14.5 MPG city driving. Might as well be driving a truck.
  • quietproquietpro Posts: 702
    Sounds like you left the parking brake engaged. ;) Seriously, though, you must have some serious issues unless maybe you're using the trip computer and have never reset it for a fresh reading. Another poster was having terrible averages and I believe it turned out that she had never reset her trip computer. Is that a possibility?
  • thegraduatethegraduate Posts: 9,731
    Depending on the ratio of "stop" to "go" that mileage may be accurate. Very short trips, and lots of idling time really knock mileage down.

    Tell me steve, what kind of mileage did you get in previous vehicles in the same conditions/average speed?
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    We rented a 2007 (or 2008, I actually didn't notice) 3.5l Impala for a long weekend trip to Kansas City recently. I put over 1,000 miles on the car, and had the compressor running pretty much the entire time (AC on the drive up, and defroster running all the way back), and averaged 29 MPG. The DIC showed closer to 31 MPG, but when I got back and tallied up the receipts, it came out just over 29. Still not bad considering there were four of us plus luggage in the car most of the time, and I was driving 70+ MPH for the bulk of the trip.

    My only complaint about the car was the lack of a center armrest (and more importantly, cup holders) for the rear seat passengers; otherwise it was a great Interstate cruiser.
  • dave8697dave8697 Posts: 1,498
    I read a lot of differences in mileage reports. There are a few key factors and a few medium factors in mileage. Key ones are how much braking, how much accelerating, and how much % of time just cruising in high gear. Medium factors are correct tire pressure, clean air filter and how fast acceleration is. Other factors are if you are a drafter or a draftee, wheel alignment, tire type, engine tune, flatness of terrain and how fast you go on the interstate. Aerodynamic Drag is a function of velocity squared. At 70 mph, relative drag effect is 4900. At 80 mph, drag effect is 6400. 14% more speed created 31% more drag force on vehicle. Luckily, mileage doesn't drop 31% when you speed up to 80 mph due to high powered engines and well designed transmissions in cars. Even wind can effect mileage. If I drive into the wind both ways on my 47 mile commute, it will reduce my mileage. I Think The best way to compare mileage is to take a 200 mile trip at no more than 75 mph and report that number only. Any city number or number for a short stop and go commute is greatly affected by the factors listed.

    I drive my son to college in his V6 Mustang too often and it's an 85 mile trip of which only 30 miles is on an interstate. I counted the lights and discovered there were 60 of them. Thats a stop at an average of every 1.4 miles. The car gets 29 mpg on these trips. I thought it was highway driving until I counted all the lights. It gets 29-30 driving the 47 mile commute to work. Even With heavy stop and go rush hour traffic averaged in, it gets 27-28. The stop and go driving is 20% of the trip distance but adds 20 minutes to the time to get there or back. I do not know the true trip mileage for the car, but don't expect more than 31.

    I see a special price on an '08 Impala locally and the opportunity won't come around again. The LS model with a 3.5 liter V6 seems to be capable of low 30's on a trip according to some posters here. My work commute usually gets me 28 mpg for my 3800 Buick and 29 mpg for the 3.8 L Mustang. Based on this I think the Impala could get 29-30 commuting. The Impala is a lighter, smaller, lesser powered, smaller engined car than my Buick.

    When I looked into a Cobalt, I was expecting about 32-33 for my commute but didn't get one. This Impala opportunity is at a better price than the Cobalt price was at the time. Can anyone say that the Impala 3.5 is not capable of better mileage for me than my pair of 3.8 liter cars (28 and 29)?
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    I've got a 2000 Impala with the 3.8, and my highway mileage runs comparable to your own experience. While I don't own a current issue Impala, I've rented one two or three times. I was a little disappointed with the mileage on this most recent trip (almost all highway, but didn't average over 30 MPG as hoped). However, a couple of years ago I rented a 2006 model (3.5l), and driving from southern Illinois to Terre Haute, IN at the posted 65 MPH speed limit (and with the AC on), we averaged at or just over 36 MPG (both on the DIC and manually calculated). I posted the precise results on Edmunds somewhere, possibly in this same forum (though I don't remember).

    If my commute involved a lot of highway miles, I wouldn't hesitate to buy a 3.5l Impala. On the worst of days it'll equal the best mileage you're getting with the 3.8l cars, and on it's best days it'll do much better.
  • My 2008 LTZ has 4900 miles and produces 25.9573 MPG since new. The worst was 20.6 MPG, the best 30.1 MPG. I think it may get better when and if it loosens up. It still feels tight- doesn't seem to roll freely. I am basically satisfied with the fuel mileage. The car otherwise, is perfect. My 30.1 MPG stint was about 240 miles on I-75 in Michigan at 65 to 70 MPH.
  • quietproquietpro Posts: 702
    I just finished a trip for the Thanksgiving holiday and set a new record for gas mileage with my SS. I would like to look at a topographical map to confirm my suspicions but I believe I'm gettng better mileage based on a overall down slope on the trip. I fill up at the same gas stations to and from my destination so I can gauge the difference in each direction of travel.

    Here are my results:

    Northbound legs
    25.34 mpg/54.1 mph and 27.37 mpg/67.1 mph

    Southbound legs
    29.33 mpg/69.7 mph22 and 22 mpg/64.1 mph

    I cheated a little on the 29.33 mpg leg by resetting the car's trip computer after I accelerated to cruising speed. However, the car's indicated fuel mileage was actually slightly lower at 27.7 mpg. I attribute part of this disparity to possibly filling the tank a little more prior to this leg. But, even if I added an extra half gallon at the end, which I know I couldn't have fit, the mileage would have only dropped to 28.7 mpg.

    The leg listed first is through fairly level terrain through SC, NC, and VA on I-26 and I-77.

    The leg listed second is through the mountains of VA and WV on I-77.

    These results are consistent with other trips I've taken over the same route. This is why I believe I may be seeing an overall result of uphill vs. downhill mileage over the course of the leg. It's pretty interesting, though, as my mileage has continued to improve as the car wears in. I now have about 29.5K on the odometer. Regardless, getting over 25 mpg, UPHILL, with a V-8 engine producing over 300 HP is damned impressive. One last note, I achieved these latest results on 87 maybe I was producing a little less than 300 HP. The lower octane doesn't seem to affect fuel economy so I plan to use it for the road trips from now on. ;)
  • pulgopulgo Posts: 400
    You say:
    "I cheated a little on the 29.33 mpg leg by resetting the car's trip computer after I accelerated to cruising speed. However, the car's indicated fuel mileage was actually slightly lower at 27.7 mpg. I attribute part of this disparity to possibly filling the tank a little more prior to this leg. But, even if I added an extra half gallon at the end, which I know I couldn't have fit, the mileage would have only dropped to 28.7 mpg. "

    To calculate MPG one should simply divide the miles traveled by the amount of gallons on the receipt after the fill up.

    Using the computer won't give meaningful numbers.
  • quietproquietpro Posts: 702
    The computer on the 06+ Impalas is actually pretty accurate. While I never get the same number when calculating mileage manually, it's usually within .5 mpg.

    You are assuming too much when you state that all that is required to calculate mileage is to divide the miles by gallons at fill up. Filling a fuel tank isn't an exact science since the cutoffs at various pumps will vary. Also, most people usually pump to an even dollar amount. You can never be certain you have filled your tank to the exact same posiiton everytime. That's why I go with averages to compensate for those variances. As I stated, I believe I pumped a little more fuel into the tank before that last leg than I did at the conclusion. That would give the impression that I achieved better fuel mileage than if I managed to squeeze an extra half gallon or so into the tank. I acknowledged that in the post (accounting for mileage if I were to calculate based on an extra half gallon of fuel).
  • pulgopulgo Posts: 400
    To eliminate all those variances I calculate my mileage averaging the last 10 fill ups. This would be for approx. 4k miles.

    Since I always drive the same route the only major changes happen when the colder (not really very cold) season starts in November or when it starts to warm up in March.

    Here in Vancouver, BC, the lowest temperatures we get are around 20 degrees F and don't stay for long periods of time.

    By the way, I own a 2007 Sentra that is in for service today and the loaner I got is a 2007 Impala. What a nice car! If I believe the computer I am getting 32 MPG on my commute and that would be awesome!
  • quietproquietpro Posts: 702
    I average as much as possible but my commute often involves traffic jams which aren't uniform. The best I can do is average over the last few trips which WERE consistent even though temperature and speed will vary slightly.

    32 mpg in a V-6 Impala is very feasible...especially with the 3.5L engine.
  • zeeboyzeeboy Posts: 25
    Seems the 3.5 V6 is nearly as fuel efficient as the new Malibu in real world numbers.
  • Does anyone know a practical / economical way to change out the 3.29:1 axle ratio on the LTZ (3.9L engine) for the 2.86 ratio from the 3.5L engine?
  • lostwrenchlostwrench Posts: 288
    I'm getting 32 mpg hwy with my 2004 Impala, but it has the 3.4L engine.
  • superdowsuperdow Posts: 2
    My 3.4L 2002 impala has about 110,000 miles.
    I just got 33.5 mph on the "highway." That included driving through a few small towns with stop and go traffic.
    Most of it was 55 - 65 mph.
    City driving is about 25 - 27
    I try to "hyperdrive" by anticipating stop lights and stop signs. No jack rabbit starts.
    Lots of coasting when possible.
  • bena8837bena8837 Posts: 26
    I have a 02 impala with 3.4 and was getting about 31 MPG on highway and around 28 in city. It seems suddently I lost about 10 MPG and I have tried everything I know and even had it diagnosed at a Best of the Best Shop. They told me the ejectors were dirty and needed cleaning, got it done there. No change. The Spark Plugs have been replaced with original kind, Fuel Filter replaced, Air Filter changed, MAP Sensor Cleaned, Fuel Valve checked, and problem has not been resolved.
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    How many miles do you have on it? Could it be your catalytic converter is getting clogged? If you feel like you're losing power as well, that might be the culprit (I never had a problem with mine, but I know others here has posted stories about the converter clogging up and causing power/economy problems.
  • bena8837bena8837 Posts: 26
    I started writing about a 10 mile loss in mpg several months ago. I tried everything I knew could be the problem by replacing the spark plugs(which appear to be fine), Air Filter, Fuel Filter, Cleaning the MAFF ? Filter on the air intake with spray, and finally had it taken to a (Best of the Best) Shop and had it (analyzed). They told me the ejectors needed cleaning and I said Ok. Drove it home and no change. Since then, when I have time I go under the hood and look at possibilities. About 3 weeks ago I notice moisture aroung the Coolant Temperature Sensor. So I decided to replace it. I drove to Dallas about a week later and guess what, I regained my MPG, 31+. Also, on the way there (about 400 miles away) I started having problems with the catalytic Converter and had it replace when I got there. It was still in warranty since my car only has 60K. My car always appeared to run in a temperature of about 191 degrees, which I believe I had read was within range. Heads Up to everyone who owns car with 3.4. Thanks for your help, appreciate it!
  • Just bought this Impala and first 750 miles with computer average is 22.7 in mixed highway and city driving with plenty of short run ins. This Impala is 3.5 L with 18" wheels and sports tuned suspension. I guess it will increase as this is break in period. Noticed big difference with 18" wheels and tight suspension as it stick to the roads. I wondered if this affects fuel consumption as well.
  • nosirrahgnosirrahg Little Rock, ARPosts: 872
    Sticky tires will likely decrease your mileage; also if the diameter of your new wheels & tires is bigger than the factory setup, your speedometer/odometer may be off somewhat and give you a false (lower) reading.
  • this is factory installed. Came with 50th anniversary Impala and I guess the speedometer is adjusted from the factory as this was standard on the vehicle. Will post as I drive more about the mileage and alco check between fillups to ensure that computer mileage ie similar.
This discussion has been closed.