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By pgwerner, March 4, 2006

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I just bought a new Corolla less than a month ago - a 2005 Corolla LE, with only 12000 miles on it. I bought it from a dealership and its a Certified Used Vehicle. I've filled it up twice so far and have been keeping track of mileage.

Here's the problem - its only getting about 24 mpg. Its mostly city driving, but a 2005 Corolla is estimated as getting 32 mpg city. My previous vehicle was a 1995 Corolla, and it got about 30 mpg under the same driving conditions.

I'm in the San Francisco area, if that makes a difference - its winter, but our winter weather is pretty mild.

The car handles well and exhibits no other odd symptoms. I'm still under full manufacturers warranty – do I have a warranty claim based on the fact that the mileage isn't what it should be?

Thanks,

Peter

I don't think you will be able to get any type of warranty claim out of this. If they can't or don't find anything wrong with the car they can always just say it is your driving habits. I didn't see it in your post but is this car auto or stick, and same for your previous car.

Here are some things to check for.

1 -Since this is used the first thing you should do is use a fuel system cleaner. No telling what type of gas the previous owner used. I lose about 4mpg, from 42 to 38, going from Shell gas to Sam's Club gas. I have to attribute this to a cheaper grade of gas and can only assume it is going to dirty the fuel system much faster. The fuel system cleaner I have been the most impressed with is Chevron.

2 - You also don't know where the previous owner has been driving. Check/clean/replace the air filter.

3 - Are the stock tires/wheels still on the car. This can make a HUGE difference in gas mileage. I would also suggest running above the recommended 30 psi. I keep mine at about 35. Running a higher pressure, but not overinflated so that you get heavier wear in the center of the tire, will net you better gas mileage and longer tire life.

4 - When you get the chance make the conversion to synthetic oils. This would include engine, transmission, and differential.

5 - Driving style. Accelerate slow and smooth. More coasting and less braking.

Hope this helps.

Those are all excellent suggestions.

I find warming the car up in the morning, even for as little as five minutes, has a noticeable effect when I calculate my MPG.

I've never gotten anywhere near 24, but have flirted with 30 when my daily drive is under 6 miles total a day.

I have 2005 Corolla CE with manual transmission. Winter mileage is around 38 MGP, summer mileage is around 36 MPG.

It is possible that someone put the wrong grade of oil in the car. It should be 5W30.

Does it have Goodyear Integrity tires? Mine only lasted 20,000 miles. I went with Michelin Harmony, they have a low rolling resistance. I keep them at least @ 30 PSI. Must check PSI with each season change. The air conditioner robs 2-3 MPG, and it runs with the defroster....but sometimes this is necessary.

Some cheap gas does not give same MPG as some name brands. I have good luck with BP/Amoco.

Every 5000 miles you could put in a bottle of Techron fuel injection cleaner (for 12 gallon tank size).

Go back to the dealer you bought the car from and complain about the mileage . You need to start a documented history of the car and mileage complaints. Follow your manual's advice for gas and oil changes.

Any changes you make that are not authorised by the dealer or their rep can affect your claim for the vehicle's poor performance.

Try the dealer first and go from there. They can run scans and diagnostics on the car but you need that written complaint and followup for any future compensation.

You are getting good advice about gas and tires and stuff but you need that documented history from the dealer before you make changes in my opinion.

I have 2005 Corolla CE with manual transmission. Winter mileage is around 38 MGP, summer mileage is around 36 MPG.
You get better mileage in the winter than the summer? default_huh or is that a typo?

 

 

Bikeman982

In case you are unaware - you get zero miles per gallon with the engine running and you are sitting in traffic. Have you noticed there are a lot of hills in San Francisco? Is the car standard and you are using more gas to keep the car going up those hills in the forward direction? You could need a tune-up (it never hurts to have it properly tuned, as far as mileage goes). It could also be tires (as previously mentioned) or driving habits. Lots of factors affect the gas consumption rate. Hope this helps.

Abnormal gas cunsumption is a common complaint for 05 auto corollas. I'm not sure about manuals, but if you search yahoo auto or other corolla forums, there are two distinct groups - one getting expected/above expected gas mileage, the other getting around ~25 mpg. This issue has been bothering me for a long time, since my car is 05 auto too and I get arounf 25 mpg. No one seems to know exactly how to explain such two distinctive groups. I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs. One from Denso and the other from Delco. Corollas get equipped with either the ECU from Denso or Delco. It might be possible that one of these ECUs is causing bad gas mileage. Unfortunately, the only way to tell what ecu you got is to physically check by taking off the glove box compartment.

Bikeman982

Abnormal gas cunsumption is a common complaint for 05 auto corollas. I'm not sure about manuals, but if you search yahoo auto or other corolla forums, there are two distinct groups - one getting expected/above expected gas mileage, the other getting around ~25 mpg. This issue has been bothering me for a long time, since my car is 05 auto too and I get arounf 25 mpg. No one seems to know exactly how to explain such two distinctive groups. I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs. One from Denso and the other from Delco. Corollas get equipped with either the ECU from Denso or Delco. It might be possible that one of these ECUs is causing bad gas mileage. Unfortunately, the only way to tell what ecu you got is to physically check by taking off the glove box compartment.
Is that confirmed that gas mileage is dependent on what brand of ECU?

 

 

Abnormal gas cunsumption is a common complaint for 05 auto corollas. I'm not sure about manuals, but if you search yahoo auto or other corolla forums, there are two distinct groups - one getting expected/above expected gas mileage, the other getting around ~25 mpg. This issue has been bothering me for a long time, since my car is 05 auto too and I get arounf 25 mpg. No one seems to know exactly how to explain such two distinctive groups. I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs. One from Denso and the other from Delco. Corollas get equipped with either the ECU from Denso or Delco. It might be possible that one of these ECUs is causing bad gas mileage. Unfortunately, the only way to tell what ecu you got is to physically check by taking off the glove box compartment.

Is that confirmed that gas mileage is dependent on what brand of ECU?

 

No, Im just proposing a hypothesis. I may be wrong about ECU causing bad gas mileage.

 

 

Bikeman982

Abnormal gas cunsumption is a common complaint for 05 auto corollas. I'm not sure about manuals, but if you search yahoo auto or other corolla forums, there are two distinct groups - one getting expected/above expected gas mileage, the other getting around ~25 mpg. This issue has been bothering me for a long time, since my car is 05 auto too and I get arounf 25 mpg. No one seems to know exactly how to explain such two distinctive groups. I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs. One from Denso and the other from Delco. Corollas get equipped with either the ECU from Denso or Delco. It might be possible that one of these ECUs is causing bad gas mileage. Unfortunately, the only way to tell what ecu you got is to physically check by taking off the glove box compartment.

Is that confirmed that gas mileage is dependent on what brand of ECU?

 

No, Im just proposing a hypothesis. I may be wrong about ECU causing bad gas mileage.

 

I know there is a different ECU for automatic than there is for a standard, and of course there is always a difference in gas consumption for those two.

 

 

yeah autos and manuals get different settings/values in their ecu. Im trying to say that regardless of whether atuo or manual, corolla comes with 2 different brands of ecu. Manual doesnt come with one beand of ecu and auto doesnt come with the other brand of ecu. They both either come with an ecu from Denso or Delco.

You can get more info about the two ecu that comes with 9th generation corolla on the repair manual-> 10 Egine control system -> ECM on page 967

Bikeman982

yeah autos and manuals get different settings/values in their ecu. Im trying to say that regardless of whether atuo or manual, corolla comes with 2 different brands of ecu. Manual doesnt come with one beand of ecu and auto doesnt come with the other brand of ecu. They both either come with an ecu from Denso or Delco. You can get more info about the two ecu that comes with 9th generation corolla on the repair manual-> 10 Egine control system -> ECM on page 967
I understand what you mean and if it was confirmed that one brand was superior to the other, I would opt for the one that was better. I have changed out lots of ECU's and it is not very difficult.

 

 

I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs.
what highway mileage do you get?

 

 

I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs.

what highway mileage do you get?

 

Around 28 going about 70mph, probably close to 30 if I drove around 60 mph.

Since Bikeman says that it is not difficult to change the ECU, you might actually want to swap your ECU and see if your hypothesis is true.

What comments do the dealers have on this topic?

friendly_jacek

Abnormal gas cunsumption is a common complaint for 05 auto corollas. I'm not sure about manuals, but if you search yahoo auto or other corolla forums, there are two distinct groups - one getting expected/above expected gas mileage, the other getting around ~25 mpg. This issue has been bothering me for a long time, since my car is 05 auto too and I get arounf 25 mpg. No one seems to know exactly how to explain such two distinctive groups. I bought my car new, and my first gas mileage was 24 mpg, and my best was 28. Most of the time I drive conservately, not reving above 3K rpm. It seems though, no matter how conservatively and fuel-efficiently you drive, the unlucky owners of one group of corollas can never get close to the expected gas mileage. I am aware that corollas come with two different ECUs. One from Denso and the other from Delco. Corollas get equipped with either the ECU from Denso or Delco. It might be possible that one of these ECUs is causing bad gas mileage. Unfortunately, the only way to tell what ecu you got is to physically check by taking off the glove box compartment.

Interesting idea about the ECUs. According to my info, MT is always Denso, AT is either Denso or Delco. Furthermore, some Delco ECUs are non-reprogrammable.

I also have suboptimal MPG, get only 30 on hwy and 27 city with gentle driving. I will check my ECU and report back.

Warming a car up is unnecessary - it doesn't decrease engine wear, creates extra pollution, and will reduce MPG. Engine wear comes from the cylinders moving, not from driving the car (and the cylinders cycle regardless of whether the car is moving or idling). This type of engine wear is unavoidable.

On the road, even in cold weather (20s & 30s), my 2004 begins warming within 1 mile.

My manual 2004 gets excellent mileage: 40-42 summer, 37-39 winter. In San Francisco, I could understand an automatic getting particularly poor mileage because of the many hills, but 24 seems very low.

One of the biggest contributers to driver induced poor mileage is rate of acceleration from stops. (yesterday driving to work, a Prius in front of me shot forward at green lights. I'm sure he's wondering "why do I get terrible mileage?"). Aggressive driving has become so standard, that EPA is even considering changing MPG testing to account for it.

As has been suggested, I keep my tires firm and this contributes to the good mileage. I use the defroster and a/c minimally.

Finally, if there are problems with your ECM, emission testing should find this (if poor MPG is from incomplete combustion of fuel, this will create increased CO and hydrocarbon emissions.) If the engine is functioning normally & passes the emissions check, the problem resides elsewhere.

friendly_jacek

Warming a car up is unnecessary - it doesn't decrease engine wear, creates extra pollution, and will reduce MPG. Engine wear comes from the cylinders moving, not from driving the car (and the cylinders cycle regardless of whether the car is moving or idling). This type of engine wear is unavoidable.

On the road, even in cold weather (20s & 30s), my 2004 begins warming within 1 mile.

My manual 2004 gets excellent mileage: 40-42 summer, 37-39 winter. In San Francisco, I could understand an automatic getting particularly poor mileage because of the many hills, but 24 seems very low.

One of the biggest contributers to driver induced poor mileage is rate of acceleration from stops. (yesterday driving to work, a Prius in front of me shot forward at green lights. I'm sure he's wondering "why do I get terrible mileage?"). Aggressive driving has become so standard, that EPA is even considering changing MPG testing to account for it.

As has been suggested, I keep my tires firm and this contributes to the good mileage. I use the defroster and a/c minimally.

Finally, if there are problems with your ECM, emission testing should find this (if poor MPG is from incomplete combustion of fuel, this will create increased CO and hydrocarbon emissions.) If the engine is functioning normally & passes the emissions check, the problem resides elsewhere.

I'm not the original poster but your advice is insulting. If you reread the very first post, you will find the poster used to get 30mpg in old Corolla and is getting 24mpg in the new one WITH THE SAME DRIVING STYLE.

My corolla also has suboptimal MPG REGARDLESS of driving style. I get 27mpg in city with regular driving and 28mpg with super duper granny driving (keeping RPM under 2000). I also get disapointing 30-31mpg on hwy. So, I'm very sympathetic to the original poster's cause as I went through the same disappointment. The car now has 30000 miles and it's the same, so don't count on improving. BTW, I keep tires inflated to 36 psi and observe all precausions to save fuel.

Clearly, some corollas are not as efficient as others and it would be nice to discover the root cause. Blaiming on the driver is contraproductive.

When one buys a used car, is there a simple way to tell whether a previous owner has put in a "performance chip" that replaces the stock computer? Can the computer ID be read from some diagnostic terminal? Or do you have to take things apart to see what is there?

Bikeman982

I believe owner's manuals recommend at least one minute after start-up before proceeding just to get the oil and fluids circulating. It sounds logical to me to help the moving components last longer.

friendly_jacek - Point taken. You're correct, I didn't read the original post carefully enough.

Bikeman982

There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.
Yes, you're right. I am not trying to argue with anyone, but how do you explain an almost brand-new 05 corollas, and with my and many other cases who drive conservatively, with no long warm-up in mornings, and who kept thier tires inflated above 30psi, get nowhere close to expected gas mileage? Even with normal highway driving, why is there one group who gets sub-par gas mileage while the other group with almost identical driving gets superb gas mileage? Some people argue that EPA or whatever the organization is testing gas mileage use a controlled condition so the actual gas mileage is lower. If so, how do you explain a group of people who gets expected and in some cases above expected gas mileage with a same car? Why is there such a distinct, clearly identifyable groups each with a common, distinctive trait- gas guzzlers and gas sippers? Can normal human error create such big of a difference? Search yahoo auto and other corolla forums and read what owners say about thier corolla's gas mieage- clearly its obvious that people either complain or praise about thier gas mileage.

 

.... I appologize, I just had to write down every question I have because the main reason I got a corolla is because of its excellent gas mileage according to the sticker. I feel let down and dissapointed because no matter how conservatively I drive, the best i got so far was 28 mpg on highway, without speeding or flooring every minute. I am more inclined to drive conservatively just to try to achieve such a great gas mileage that so many people with same corollas do, which never seems to happen in case of my car no matter my effort. My dealer declined my complaint about my gas mileage and said "its normal". I am suspecting more of a mechanical factor infulencing the gas mileage rather than human error. This is why I asked about the ECU. Thanks for reading.

Bikeman982

There is always a range of gas mileage consumption based on variations of city and highway driving. That can also vary depending on driving style as well as car conditions. A well-tuned car with everything else equal will get better gas mileage than the same car out of tune. Tire sizes and air pressure can also make a difference. There are occassions when operator errors can decrease fuel efficiency. Everyone seems to be searching for the golden goose that will give them the most miles per gallon of gasoline. I am just glad I can get from point A to point B without it breaking down or having to refuel too often.

Yes, you're right. I am not trying to argue with anyone, but how do you explain an almost brand-new 05 corollas, and with my and many other cases who drive conservatively, with no long warm-up in mornings, and who kept thier tires inflated above 30psi, get nowhere close to expected gas mileage? Even with normal highway driving, why is there one group who gets sub-par gas mileage while the other group with almost identical driving gets superb gas mileage? Some people argue that EPA or whatever the organization is testing gas mileage use a controlled condition so the actual gas mileage is lower. If so, how do you explain a group of people who gets expected and in some cases above expected gas mileage with a same car? Why is there such a distinct, clearly identifyable groups each with a common, distinctive trait- gas guzzlers and gas sippers? Can normal human error create such big of a difference? Search yahoo auto and other corolla forums and read what owners say about thier corolla's gas mieage- clearly its obvious that people either complain or praise about thier gas mileage.

 

.... I appologize, I just had to write down every question I have because the main reason I got a corolla is because of its excellent gas mileage according to the sticker. I feel let down and dissapointed because no matter how conservatively I drive, the best i got so far was 28 mpg on highway, without speeding or flooring every minute. I am more inclined to drive conservatively just to try to achieve such a great gas mileage that so many people with same corollas do, which never seems to happen in case of my car no matter my effort. My dealer declined my complaint about my gas mileage and said "its normal". I am suspecting more of a mechanical factor infulencing the gas mileage rather than human error. This is why I asked about the ECU. Thanks for reading.

Well, besides the differences in climates at their locations, there is also individual vehicle characteristics (even though they may seem identical). I don't think there is any clear-cut distinctions. I think there is probably a variety of people who (not all are here to post) get a range of mileage per gallon figures.

 

Not that anyone would possibly do it, but some could be slightly exagerating?



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