Edmunds dealer partner, Bayway Leasing, is now offering transparent lease deals via these forums. Click here to see the latest vehicles!

Toyota Prius MPG-Real World Numbers

1…457910…20

Comments

  • railroadjamesrailroadjames Member Posts: 560
    So many things come into play when investigating your mpg. Cold weather drops it considerably..."ICE" has to run considerably more for heating. Another factor: Winter blend of fuel that drops mpg's. With 56K miles under my belt I've seen these things effect milage often. Be patient as the weather warms up and you should see 36-40 cold season & 42-47 warm season (or there about) DON'T EXPECT the 60 mpg since that's "EPA'S" fantacy estimate. Really now!! Did you actually expect those rediculous #'s?? Just remember a Hummer gets 7-8 mpg's.(that's roughly 280 miles per tank and nearly $100.00 fill ups @$2.55 per gal) My best example: 543 miles per tank...$24.44 fill-up 10 gallons) Nuff said!! :)
  • shammshamm Member Posts: 10
    I wondered about this kind of mileage too. We only got down to about 35mpg which was too low for me. Then I did some homework. It seems that the good mpg only comes when you keep the speed below 40. Above 40, the Internal Combustion Engine (ICE) runs, even if you don't really need it - like going down hills. Thus your mileage will go down when you cruise above 40. All the streets around here are posted at 40 and no one drives that slow, so it's either go faster than 40 and lower the mpg or get run down. For one tank I did keep the speed below 40 and the mpg did go up to 45, so that did work.
    Also, the oxygenated fuel lowers your mpg.
    And the heater only running off the ICE which cuts the mpg.
    But the car is still really nice and when you manage your speed and have nice warm weather, you'll see better mpgs.
  • boraboraborabora Member Posts: 16
    thanks for all your tips.
    i drove the car for another 30 commuting miles yesterday and today. seems the number gets better. 40mpg average.
    then i reset consumption for the last 3 mile really jammed high way, turns out to be 70mpg.
    the tip is that, dont step on gas unless you have to... :)
    once the gas engine kicks in, the consumption goes up.
    it will be a nice commuter car...
  • bakaronibakaroni Member Posts: 10
    We've driven about 390 miles in our new Prius so far and we've got 50.5 mpg so far. The driving so far includes a good mix of city, highway and mountainous roads. Love the car so far.
  • kdhspyderkdhspyder Member Posts: 7,160
    ... to whom I've sold two Prius' stopped by today to see when the next Gen will be out.

    He's at 140,000 miles in 38 months (!) in all kinds of driving and sits at 48 mpg over the life of the vehicle.... and...still on the original set of brakes.

    When mine comes out of the body shop :surprise: I will be at 15 months, 41,000 miles and also at 48.1 mpg lifetime ( GreenHybrid ) ... and the original set of brakes. I get 51-52 mpg in spring, summer, fall and 44-45 mpg in winter.
  • boraboraborabora Member Posts: 16
    I found the tip really is not to press gas too hard. but it is not practical if there are vehicles behind you. so i accelerate asap and use the electric motor to keep the speed.
  • luckyboyluckyboy Member Posts: 12
    only had 2 tanks so far and getting 47.5mpg, I am happy!
  • bakaronibakaroni Member Posts: 10
    Yes, easing up on the gas pedal conserves a lot of gas. My other car is a 5-speed VW Passat, which displays mpg stats, too, and I've learnt a lot of tips on efficient usage of gas over the years driving that car. For example, I coast a lot, which is easier with a 5-speed than with an auto.
  • ck90211ck90211 Member Posts: 159
    I parked my Prius for 2 weeks, and upon return found the mileage to be at least 3-5 mpg less than before (I usually get 48+). Weather in SoCal has been warm, so probably not weather related. Does anyone have similar experience? Or is it something to do with summer blend gasoline in SoCal? Thanks.
  • shammshamm Member Posts: 10
    Absolutely correct!
    But don't bump your Prius into Neutral! Just let off the gas and let the motor turn into a generator - the generator creates electricity which is saved in the batteries. This "regenerative braking" is a critical factor in getting good miles per gallon. Truly coasting in a Prius will reduce your MPGs.
  • pathstar1pathstar1 Member Posts: 1,015
    Check your tire pressure. Most owners find running 42 front and 40 rear gives the best mileage. Your tires may have lost some pressure over those two weeks, or someone may have let some air out.
  • pathstar1pathstar1 Member Posts: 1,015
    Actually that's not totally correct. If while in "D" you let off on the gas just enough to make up for fictional loss, you are coasting in "stealth mode", the most fuel efficient mode a Prius can use. Will not work above 43 MPH however as the ICE will not shut down.
  • boraboraborabora Member Posts: 16
    I drove about 20 miles to work. my first tank worked out 46.7mpg. not bad. i am in the start of second tank now. i just tried cruise control around 60mph today on the trip, turns out better -49mpg. the current mpg is always above 75mpg. hopefully this tank will turns out much higher than the first, thanks for cruise contr :P ol.
  • trojan4lifetrojan4life Member Posts: 2
    Not on the LA freeways i drive. My last car had a driver's information center that showed my average speed (in a Corvette no less) in LA traffic at 34mph. :surprise:
  • stevedebistevedebi Member Posts: 4,098
    "Not on the LA freeways i drive. My last car had a driver's information center that showed my average speed (in a Corvette no less) in LA traffic at 34mph."

    I drive those same freeways, but mostly on weekends or in the evenings.
  • norskeymannorskeyman Member Posts: 8
    :confuse: I have put about 300 miles on my new '07 Prius, with combined city and highway travel. I typically get about 38 average MPG, according to the info display. It has been a bit cool (in the 20's & 30's), so I've run the heater set in the low 70's, so that might have some effect. Still, I'm disappointed at 38 MPG. I can get that MPG without hybrid technology, on several small cars, including the new Honda Civic or Toyota Corolla, which are priced at least $5,000 less based on the options I have. I paid a premium price to buy high MPG, so the cost at 38 MPG is hard to justify.

    Is the MPG better after a few thousand "break in" miles? Is there anything I should have Toyota service check?

    Norskeyman
  • backybacky Member Posts: 18,949
    Have you obtained 38+ mpg in a car like a Corolla or Civic, driving the same routes under exactly the same conditions? Or are you supposing you could get 38+ mpg in a Corolla or Civic under those conditions? If the latter, I suggest you check out the Real-World fuel economy discussions for those cars. I think you will see that averaging 38+ mpg on a Corolla or Civic in cold weather and a combination of city and highway driving is not very realistic.

    I think you'll find that as weather warms up, your fuel economy will improve. You will also probably learn how to drive the Prius for maximum fuel economy, e.g. coasting as much as possible to use the regnerative braking, and using a light foot on the gas to stay in electric mode as much as possible.
  • carbotcarbot Member Posts: 14
    My '04 Prius will turn over 145,000 miles next week, at 39 months old. It is my business car and I drive for production, not mileage. Getting there means money for me. I have kept a log of every tank of gas I have put in the car, and am getting an "honest" 48-52 MPG, figured by dividing gallons into miles, not using the gage. I never have the windows down, and most of the time have the AC or heat on. Surprisingly enough, the thing that causes the biggest variable in my mileage, is the age of the tires. I keep them pumped to the max, and when the tires get close to replacing, the mileage is at its best. As soon as I get new tires, the mileage goes down drastically. Still on the original brakes. It's the perfect business car. I love my Prius. Waiting for the "plug-in".
  • gagricegagrice Member Posts: 31,450
    Smooth tires have less rolling resistance. Lots of tread more resistance. They are safer than the baldy tires.
  • shammshamm Member Posts: 10
    If you trace back through my history, you'll find a very similar posting from me. I too get about 38 mpg most of the time with my '05 Prius. But I know how to get 45... it's just that driving that way is hard to do.
    1. Gradual starts from stops - no jackrabbit starts!
    2. Keep the speed under 40mph - above 40 (or 43 depending on lots of circumstances) the engine runs regardless of needing it or not.
    3. Keep the tires inflated. Some people set them at 40psi, others go to 42psi. More pressure, less rolling resistance.
    4. Keep the windows up. The A/C will drag you down some, but not as much as the air drag with the windows open.
    5. When you see the traffic light ahead turn amber, take you foot off the gas. Let the motor become a generator and return some energy to the battery. This makes you slow down more gradually than many people want to slow down, but it really does help the MPGs. Hard braking uses the mechanical brakes on the car - just like everyone else. But braking with the generator returns lots of power to the batteries, so let it! No, you don't need to shift to "B". That's used when you're coming down steep hills and you don't want to ride your brakes. It's the same as downshifting.
    6. Don't carry excess weight; carrying four passengers, a trunk full of books or other heavy loads will reduce mileage.
    7. I bet there are other ideas that others will suggest. Try them all!
    Enjoy the car for all the other reasons. It is very comfortable, easy to drive, roomy, comfortable, etc.

    Following these practices, I can make my Prius return about 45mpg. (Less in winter with oxygenated fuels.) To do it, I had to drive in the right lane and use the cruise control to keep from going too fast. Most of our major streets are four lanes and posted at 40 and everyone goes 45 - naturally. So stay right and let them pass you. And smile as you see much better MPGs on the dash.

    By the way, no one recommends using a cruise control in heavy traffic. It will take too long to react when some knuckle head does something stupid.

    shamm
  • norskeymannorskeyman Member Posts: 8
    In my area, gas contains at least 10% ethanol. That has to hurt MPG a bit.

    I have had other cars with better MPG than what I'm getting with my new '07 Prius. I had a 3-cylinder Geo Metro that consistently got 50 MPG. I had another Metro, but with auto transmission, that only got 40 MPG ... but that's still better than my Prius, thus far.

    I may try driving no more than 40 mph in the city, but that is inconsiderate, not to mention a bit dangerous, if the normal flow is a bit faster, say 45 mph, and others are held back. I've always felt that slow drivers who gum up traffic flow create as many frustrations and accidents as the speeders. For safety's sake, it's best to drive the prevailing speed of existing traffic. Just a personal opinion. Norskeyman
  • backybacky Member Posts: 18,949
    Comparing the fuel economy of a mid-sized car to a tiny, under-2000 pounds 3-cylinder econobox is not relevant, IMO. You might as well compare the fuel economy of a moped to the Prius. The moped will beat the Prius' FE, also.
  • cheryl06priuscheryl06prius Member Posts: 50
    I just computed the MPG on my 06 Prius from 03-14 to 04-14 and it is reassuring: 2031 miles, 38.9 gallons=52.2MPG. This is in Western New York with about a 50/50 city/highway ratio.

    Less reassuring is the fuel consumption gauge-it reads high and low-usually high, it is not at all reliable, but I do the best I can to fill the tank manually to the same level and divide it by the tripmeter reading.

    I've been using the 42front/40 rear psi tire pressure setting. However i've noticed every time I take it to a Toyota dealer or Walmart for an oil change or tire rotation, they lower the pressure to the psi listed on the door placard.
  • maxwell07priusmaxwell07prius Member Posts: 1
    I bought a Prius several months ago and I am tracking each mile very carefully. I record speed, terrain, gas type, and temperature. I do not change my driving habits. I could get 50MPG from my old van if I were willing to cut the engine and drive down hill in neutral.
    Since no one can control exactly how full their tank gets on a fillup; I, like you, am measuring over the long term. I am using linear regression to determine what factor causes bad gas mileage. Here are my results after 7220 miles, in reverse order of importance.

    5) Surprisingly, mountains do not decrease gas mileage by themselves, you have to use your brakes. If you take an interstate over the mountains you do not have to brake, but on other routes you may have to brake to make sharp turns; this makes a big difference.

    4) Speed. Between 45 and 65, my Prius looses about 4MPG. I suspect this extremely low figure is due to its low drag coefficient. Above 65, the MPG drops off much more steeply, as it does in all cars.

    3) The outside temperature is a big factor, for reasons explained below. My Prius loses 1MPG per 5F degrees.

    2) Length of trips. See below. I have no hard numbers on this yet, but I am willing to take previous testimony to this at face value.

    1) Gas type. E10 is a real killer. Most cars loose about 3% with E10 but hybrids do much worse. The hybrid is programmed to run the (gas) engine until it reaches a certain temperature. In cold weather it must do this longer to reach the operating temperature and during short trips it may not have time to reach that temperature. Ethanol burns at a lower temperature than gasoline; so, depending on how you drive, your engine may never reach the right temperature and the electric motor may never do its part. SUV hybrid users that use E10 do about as well as the same SUV on regular gas.

    My best advice, weak as it is so far, is to avoid E10 and 2-lane mountain roads, in that order. You probably can't avoid short trips, cold weather, and may not want to slow down.

    I will continue my experiment adding the fuel gauge issue to what I track. The gauge may be correct but a driver's ability to fill up a tank exactly the same is an issue. Even if you can be accurate to within a quart each time, that means a variation of 1/2 gallon over about 10, or 5%. This means a difference of about 2.5MPG. I suspect this variation is about 5MPG in practice.
    I do not think the air conditioner will make much of a difference (I will find out in a few months). The Prius AC runs off of the battery and not from a belt off the engine, so there is no real drag. This costs only about 75% the energy of a belted system but it will make the battery charge more and the (e) motor run less. I think it will cost between 1 and 1.5 MPG.

    I drive from Pittsburgh to D.C. several times a month and am getting 51.46 (+-0.36) MPG overall.
  • oldfordman1oldfordman1 Member Posts: 8
    51.3 mpg per the display when I filled the tank for the first time on 50/50 suburban/highway driving. If I got a full tank of gas, the figure would be about 50.8 mpg.

    If E10 gas causes the loss you describe, how much worse is E15? That's the only gas available in the DC area.
  • acdiiacdii Member Posts: 753
    So far after 2100 miles and a few tanks of gas, the display reads out 48.2, but the hand calc on the last 2 tanks came out over 50 MPG. I do mostly 50-60 MPH with some 35-45 mixed in. Mostly hills, many stops on a 35 Mile oneway trip to work, with some on battery mode through Crystal lake and Cary. I find the battery mode very touchy, I can barely touch the pedal and have the engine start, other times I can go along on just battery doing 40 MPH.
  • happyowner2happyowner2 Member Posts: 1
    I have found the most effective driving habit is that each time I take off from a stop I let off the accelerator pedal momentarily to allow the variable transmission to shift to it's top ratio, then depress just enough to maintain my speed. This, in addition to all the other previously mentioned habits is allowing my '07 to average 52-53 mpg.
    I also find that it is not necessary to drive at only 40-45 miles per hour. My best mileage is obtained on flat, open roads at around 65 mph. I have driven a little over 7000 miles since early February. Best car purchase ever for me.
  • joannerjoanner Member Posts: 10
    I just completed a trip from the Tampa Bay area to New Hampshire, over 1600 miles. My MPG "dropped" to 50 miles per gallon, both by computer and manual computation at each fill-up. As a matter of fact, the first tank of gas at the dealers got me 45 MPG (maybe they didn't actually fill er up). I've never gotten less than 50 MPG, mostly 51-53, but I've never gotten the advertised 60 MPG.

    I love my 2007 Prius.
  • rcinmdrcinmd Member Posts: 139
    What speeds were you running on I-95?

    I just completed a run down to Sebastian, Fl, and was on 95 from Florence, SC to Palm Bay. I ran about 75 mph the entire distance, ac on all the time. Per the computer, I averaged 43 mpg. The "actual" number was less per calculations, since the bladder must have expanded on the fillup down here. I was getting some new and odd "exhaling" noises coming from the tank while filling.
    Mine is a Touring, so perhaps the stickier tires do drop mileage. I have the pressures at 35F / 33R

    And, the AC blows ice cold. It was interesting to note that the ac continues to run when the ICE shuts down at a traffic light. Though the real test will be on a sunny 95 temp / 95% humidity day
  • wooha2000wooha2000 Member Posts: 54
    Just picked up my 2007 Prius Touring Package 2. I averaged between 75 and 80 mph and did ~43mpg with the Auto Climate Control set @ 75 degrees.

    This was from Las Vegas to Calgary on the I-15 about 1300 miles. The temp outside in the desert was ~90 to 100degrees and then when I got into Canada speed droped to ~65 but milage when down. ~41mpg. Windy and rainy and outside temp was ~37degrees.

    Anyone notice changes in milage with outside temp?
  • larsblarsb Member Posts: 8,204
    Sounds like you got hit by the fact that ALL CARS lose MPG in rain and all cars lose MPG when being fronted by wind.

    Since your vehicle's engine was already at operating temperatures, the colder temps very likely had any affect at all on your MPG.
  • kdhspyderkdhspyder Member Posts: 7,160
    I haven't noticed any significant change using E10.

    Here are the factors I've noticed along with their corresponding deductions from a perfect 'norm'.

    In decending order of negative effect.
    1) Towing anything is a huge penalty possibly as much as a 50% reduction in FE
    2) Lots of weight in the vehicle, passengers cargo etc. ( EPA tests are done empty ) deduct up to 20% from your 'Norm'
    3) Short trips under 10 min - deduct 20% from your 'Norm'
    4) Snow, Rain, sleet - deduct 15%
    5) Strong head wind - deduct 10%
    6) Cold weather - deduct 5 - 10%
    7) High speed driving 0ver 70 mph - deduct 5 - 10%
    8) Many starts from a dead stop ( going from stop sign to stop sign to stop sign ) - deduct 5 - 10%
    9) Winter fuel - deduct 2 - 5%
    10) Low tire pressure - 30-34 psi - deduct 2-3%
    11) Terrain - fortunately 'what goes up..' usually this balances out on a RT so there is little or no effect as you noted.
  • kdhspyderkdhspyder Member Posts: 7,160
    Actually there is no top gear in the HSD system the variations are infinite. What you are doing when you accelerate normally up to cruising speed then let off the pressure on the gas pedal is you are allowing the ICE to turn off. This is the key factor in saving fuel. The more often you can 'turn off' the ICE the more fuel you'll save. Voila.

    Actually at 41 mph and less the ICE does turn off. At 42 mph and faster the ICE turns down from normal revolutions of say 1600 rpms to an idle speed of 950 rpms. At 65 mph while cruising if you let off the pressure you'll see the 'biofeedback' bar go up to 100 mpg just the same as when you are rolling at 15 mph in heavy traffic. In the latter case the ICE is actually turned off.

    If you have the opportunity take a Sunday drive at a very relaxed pace say looking at houses or at scenery while driving at a constant 20-35 mph for say 25 or 50 miles. You should be able to average well above 55 mpg or even above 65 mpg.

    Best car purchase ever for me as well. 44000 miles in 18 months with a current economy of 51 mpg since the weather has warmed up. 48.0 mpg lifetime average fuel economy.
  • gagricegagrice Member Posts: 31,450
    Let me get this straight. If under ideal conditions I get 50 MPG in my Prius I can expect to get 5 MPG if I have several passengers on a short trip in a snow storm with high winds at 10 below zero driving 75 MPH? :)
  • kdhspyderkdhspyder Member Posts: 7,160
    If you were in that position of having to do all that then yes you could end up with single digit FE. Unlikely but possible. :D
  • mevandemevande Member Posts: 190
    Good overall #'s. It makes MOST people mad to see a Prius driver the cause of a traffic backup by going 45mph on a 50 mph road. Be real people, drive the car and not be 'anal' to try and get 3 more MPG.
  • gagricegagrice Member Posts: 31,450
    In all fairness to those that drive the Prius. I believe I have been passed on the freeway by as many Prius as I have passed. They are very visible and they do stand out when they are holding up traffic. I would like to see more tickets written on anyone that slows the normal flow of traffic. It is a hazard to all that use the freeways. You are right saving a few cents worth of gas is not worth causing a traffic problem or worse an accident.
  • stevedebistevedebi Member Posts: 4,098
    "Actually there is no top gear in the HSD system the variations are infinite. What you are doing when you accelerate normally up to cruising speed then let off the pressure on the gas pedal is you are allowing the ICE to turn off. "

    While I concur about the infinite gears, note that my ICE only Ford Freestyle also follows this characteristic. Accelerate (slightly) past the desired speed, then let off of the pedal. The computer will adjust the engine about 150 RPM slower for the set speed than would have showed if one had simply gone to the lower speed in the first place. After that the RPMs will remain stable. But the only time my ICE turns off is when I remove the key! ;)

    I realize the transmission is different from HSD, but I just wanted to mention that I found the original comment very familiar.
  • stevedebistevedebi Member Posts: 4,098
    "In all fairness to those that drive the Prius. I believe I have been passed on the freeway by as many Prius as I have passed. "

    True, but only the slow ones get noticed - of course... :sick:
  • joe63104joe63104 Member Posts: 1
    I've had my '07 Prius for about a month now, and just completed an approx. 1,000 mile round trip. At first with the Prius I was disappointed with the mpg, getting only about 46.9 avg. with the first tank of gas. That driving was a mix of back/forth to work each day, a one-way trip of only 2.7 miles, and a few freeway trips to suburbia. But I don't think the car is supposed to do so will with only short-distance trips where the engine can't even warm up. The next tank consisted of about 100 miles of said short-distance driving and 3/4th the way from St. Louis to OKC, averaging about 49. Then more city driving and back on the Interstate on the next tank. That averaged a very nice 50.5, with the next tank and final leg of the trip (back into mixed suburban/urban driving) has stayed at about 51.5.

    Hope it keeps getting better!
  • cstonecstone Member Posts: 3
    OK, so in my new 2007 Prius the manual states that when the fuel level gets low, the last "bar" on the gauge begins to flash and I should refuel (I think it says) immediately.

    Does anyone know appx. how much fuel is left at the point when the last "bar" on the gauge begins to flash? Most cars I've had in the past have said something like "you have appx. 1.2 gal remaining" in the manual.

    thanks,
    cf
  • mwbuenomwbueno Member Posts: 9
    For some reason this value seems to vary quite a bit. The furthest I have gone in my 2004 Prius is 52 miles after it began blinking & was very happy to get to a gas station.

    Most of the folks I have heard about that run out of fuel, claim they got anywhere from 35-60 miles after the blinking started however, I have a friend with a 2007 Prius that only got 12 miles after it began blinking before he ran out fuel just two weeks ago.

    Best Regards,
    Wayne
  • kdhspyderkdhspyder Member Posts: 7,160
    A good estimate is that there is just under 2 gal left in the tank, meaning that you've used about 10 Gal. I drive til it flashes and it's always around that figure.

    The reason that the amount to refill the tank seems to vary so much is the fuel bladder that's inside the tank. Depending on the weather you may get more or less in the bladder.
  • joe131joe131 Member Posts: 998
    how does weather affect the bladder's capacity?
  • pathstar1pathstar1 Member Posts: 1,015
    The bladder flexibility varies with temp. When hot it flexes well. When cold it gets stiff, and you can't get the full capacity in the tank.

    When you get down to two pips it's saying "get fuel soon". When it gets down to one pip it's saying "get fuel now". When the last pip starts flashing and the "beep" sounds, it's saying "last chance dummy, stop now or I will".

    I recommend you do not try to "push" your distance on a tank. It's not healthy to run the car out of fuel.

    For one thing, you can suddenly start to slow down when it happens, and if that occurs in certain situations you can become a traffic hazard (and you may get "run over" by someone else not paying attention).

    Second, although the fuel pump does shut off when the engine stops, it is cooled by the fuel flowing through it and that it is immersed in, so when you run out there isn't any fuel to take the heat still in the pump. This -could- shorten its' life.

    Third, there are places you don't want to leave your car while you go for fuel, or even be while you wait for fuel.

    Fourth and most important, when you run out you will have to pull of the road on battery power. Then you will have to use the battery more to get the car restarted (fuel primed) - I say "you" but the car does it automatically. You may think you can go a little farther and try to start the system a few times as well. More battery power gone. This will get the "traction battery" discharged below the desired 40% charge minimum, and that can shorten the battery life. It makes it more possible to fully discharge one or more cells, causing them to be "reverse charged" when the battery is drained further. This often leads to cell destruction and permanent loss.

    Finally, any "foreign matter" you manage to get in the tank will be stirred up most when the fuel level is very low as it will splash around in the bottom only then. Stuff such as dirt or water. It can damage the fuel pump and/or plug the fuel line filter.

    There are lots of stories posted of Prius owners/drivers running out of fuel. You'd think it would be the least likely thing to happen to the most fuel efficient main stream vehicle currently being sold but many owners want to "compete" to see how far they can go! Total silliness.
  • joe131joe131 Member Posts: 998
    seems to me 10 or 15 gallons of gasoline would warm up a cold bladder pretty fast. How much do you think the capacity varies with temperature?
  • pathstar1pathstar1 Member Posts: 1,015
    The fuel will not "warm up" the bladder. The fuel is usually colder than the air temp. I don't "think" the capacity varies with temperature. I -know- it does as just about all owners have reported it, Toyota warns about it, and I've seen it. Read your owners manual.
  • joe131joe131 Member Posts: 998
    Don't have a manual.
    The bladder would end up about the same temperature of the gasoline being pumped into it is my guess. How cold a day does it take to shrink the capacity of the bladder? On cold winter days the gasoline from underground tanks at the gas station would be warmer than the air temperature, right? But on a hot summer day the gas would be cooler than the air temperature.
  • pathstar1pathstar1 Member Posts: 1,015
    Yes, the fuel from underground tanks is pretty much the same temp year-round and doesn't vary much across most of North America. It varies by about 5 deg C. So we can rule out the fuel warming or cooling the bladder having any effect.

    Most owners report that at around 50 deg F the tank appears to loose capacity. It gets really noticeable below freezing. I forget the exact wording in the manual. But it is real. You can appear to loose 2-4 gal capacity. Usually closer to 2. Perhaps fuel vapour pressure has something to do with it.

    It's very difficult to quantify exactly, because there is no really reliable way to measure tank capacity. Most owners get used to how much fuel they should be pumping in, and suddenly notice it decrease (or increase), along with calculated mileage suddenly changing.
  • joe131joe131 Member Posts: 998
    Ok then, let's say the gasoline underground is at 62 degrees F plus or minus 5 degrees. If the outside air temperature is 23 degrees F and your tank is nearly empty, the bladder temperature is also near 23 degrees, right? Then you pump in 15 gallons of the warm gasoline. Are you trying to tell me all that gas will not heat up the bladder to about 60 degrees F or so when it refills the tank?
    I don't understand how you could think that.
Sign In or Register to comment.

Helpful Tools

Most popular vehicles