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?

 

Bikeman, you are doing exactly what DWC was trying to do, fixing the blame on the owner.

The facts are simple, the guy used to get 30 mph in 95 corolla and gets 24 mph in 05 corolla. This is not trivial, 20% loss with same driving style. Some corollas have a hidden flow making them gas guzlers. My 03 not only had less than average mpg but also sulfur smell, signs of running too rich. Yet, there are no MIL, no codes, and all sensors seem to be working well on the OBD2 scanner.

Bikeman, if you have a good explanation for this anomaly, please let us know.

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?

 

Bikeman, you are doing exactly what DWC was trying to do, fixing the blame on the owner.

The facts are simple, the guy used to get 30 mph in 95 corolla and gets 24 mph in 05 corolla. This is not trivial, 20% loss with same driving style. Some corollas have a hidden flow making them gas guzlers. My 03 not only had less than average mpg but also sulfur smell, signs of running too rich. Yet, there are no MIL, no codes, and all sensors seem to be working well on the OBD2 scanner.

Bikeman, if you have a good explanation for this anomaly, please let us know.

I am merely presenting possibilities. Without actually having the car and checking it out, I can only speculate on the cause, based on the description of the symptoms. There are similar cases presented by others and causes have not been definitively identified. The car (by your description) has had a seemingly unexplainable significant decrease in efficiency. I am not putting any blame on any owner, I am just stating that driving characteristics do have an effect on the gas mileage. That does not rule out the possibility that there is a mechanical, electrical, or other malfunction with one or several components. If there is no MIL, does that mean it is operating within the design parameters? The dealers would probably say that it is. They can thoroughly check everything out (at great expense to the owner) and come up with "nothing abnormal". We who do the daily driving of our vehicles can notice things like reduction in efficiency, while testing can only verify everything is functioning as designed. Most repair places will follow fault isolation methods and change something based on the results, which may or may not actually fix the problem. Meanwhile we have to accept the results, or continue to spend money and time trying to get it fixed. We all have the same options, some of them better than others. Hope this helps.

 

 

I think the problem is the car. not the driver. maybe it is the ECU mentioned long time ago in this thread.

I think the problem is the car. not the driver. maybe it is the ECU mentioned long time ago in this thread.

That may very well be the case and to verify it, the ECU would have to be changed and all other conditions remain the same, to be a valid test.

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.

Maybe we should test this ECU theory. I have a manual so I assume I have the Denso. I get an excellent 37mpg combined. Is there anyone with a manual that is getting really bad mileage?

 

For autos, can some people report which ECU they have and what mileage they're getting?

Congrats on the purchase, has it been serviced thoroughly? Log books can be easily made to appear if all servicing was done. It may have fouled plugs, a dirty MAF, throttle body, vacuum leak, air filter, poor quality fuel being used etc etc etc.

It could be an ECU prob, I think the best bet would be to put it on a dyno and measure AFRs or plug in a OBD tool to see if the car is running too rich from the ECU tune.

The dealer should have the software to reflash the ECU with the latest update program from the current model, if thats the case, good luck.

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.

Maybe we should test this ECU theory. I have a manual so I assume I have the Denso. I get an excellent 37mpg combined. Is there anyone with a manual that is getting really bad mileage?

 

For autos, can some people report which ECU they have and what mileage they're getting?

Good question - everyone do an ECU check.

I have an automatic and all mine (including the many I have laying around in my garage) are all Denso.

The brand of ECU can be checked without removing it. Good point about swapping it out - should not be done without knowing what effect it might have. Our intent was just to identify brands and compare gas mileages to see if there is a trend or pattern.

You guys realize that you can't just go around switching around ECUs in 2005 Corollas. They have the passive anti-theft keys programmed into the ECU. If you swap the ECU and don't have the dealer reasign the keys to the new ECU, THE CAR WILL NOT RUN. Also, I don't know if Denso ECUs and Delco units are interchangable without dealer help.

Another thing, the sticker EPA mileage is always over-inflated. To obtain this figure, they drive at 55 with no air in a closed enviroment with no crosswinds or headwinds. Drive in medium to heavy winds or above 55, or with air, and you probably won't achieve even near the EPA figure. My Dad gets 38 MPG highway driving my '05 LE Auto, but other people I know get 32 MPG, and 25 MPG highway. I have a Denso ECU. My car was built in March of 2005.

I and others have gotten the EPA milage and then some. While, I can't get it every tank due to driving too fast, too many short trips, ect. When we want, we can get a average of 36-38MPG and our record is 43MPG and that's above the EPA ratings. I do belive that the EPA ratings can only be had using summer fuel formulas.

You guys realize that you can't just go around switching around ECUs in 2005 Corollas. They have the passive anti-theft keys programmed into the ECU. If you swap the ECU and don't have the dealer reasign the keys to the new ECU, THE CAR WILL NOT RUN. Also, I don't know if Denso ECUs and Delco units are interchangable without dealer help.

Another thing, the sticker EPA mileage is always over-inflated. To obtain this figure, they drive at 55 with no air in a closed enviroment with no crosswinds or headwinds. Drive in medium to heavy winds or above 55, or with air, and you probably won't achieve even near the EPA figure. My Dad gets 38 MPG highway driving my '05 LE Auto, but other people I know get 32 MPG, and 25 MPG highway. I have a Denso ECU. My car was built in March of 2005.

I and others have gotten the EPA milage and then some. While, I can't get it every tank due to driving too fast, too many short trips, ect. When we want, we can get a average of 36-38MPG and our record is 43MPG and that's above the EPA ratings. I do belive that the EPA ratings can only be had using summer fuel formulas.

I would be very happy if the car I was driving got 36-38 MPG.

BTW, I have a 05 5sp. That does make a little difference. I also have a TRD air fitler and I run Mobil 1. Everything else on the car is 100% stock. I think it is important to keep the car as uncluttered as possible. You can't get good milage with a loaded trunk, or having too many people in the car.

You guys realize that you can't just go around switching around ECUs in 2005 Corollas. They have the passive anti-theft keys programmed into the ECU. If you swap the ECU and don't have the dealer reasign the keys to the new ECU, THE CAR WILL NOT RUN. Also, I don't know if Denso ECUs and Delco units are interchangable without dealer help.

Another thing, the sticker EPA mileage is always over-inflated. To obtain this figure, they drive at 55 with no air in a closed enviroment with no crosswinds or headwinds. Drive in medium to heavy winds or above 55, or with air, and you probably won't achieve even near the EPA figure. My Dad gets 38 MPG highway driving my '05 LE Auto, but other people I know get 32 MPG, and 25 MPG highway. I have a Denso ECU. My car was built in March of 2005.

The intention is not necessarily to swap the ECU ourselves. However, if we find a trend that people with auto transmissions and Delco ECUs get really bad mileage, then we may have the basis to ask the dealer to change it under warranty.

And yes, I understand that EPA mileage is a test that is good for comparing cars to each other, but may not represent the mileage that you get in real life. In fact, the EPA already applies a fudge factor of -10% city/-22% highway to better represent real world numbers. However, it seems that this may not be enough to represent some American drivers!

You said yourself that your 05 auto Denso gets 38mpg highway (which is actually EPA), while others get 32 or 25. What we are doing is a like a 'case-control study' if you are familiar with the types of medical trials . Basically, if a group of people gets good mileage (mid to high 30s), while another group gets bad mileage, what are the differences in their past that may have caused this? (ECU?)

I think it can be determined that with all other things being equal, if one brand of ECU gets better gas mileage than another, that the ECU which is better may prove to be the best choice as far as gas mileage is concerned. I for one would try to get mine changed.

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one

Still, I can't be entirely sure yet.

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one Still, I can't be entirely sure yet.

 

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

Thanks for the pictures. I can't tell what brand you have. Fortunately for me, mine all say the brand on the sticker. Maybe you could research the numbers on it??

 

 

I have an 06 manual CE... I drive it 20 miles each way to work at least 6 times a week and it's about 50% interstate and 50% city streets.... I had been averaging about 30-31 MPG.... This last tank I used Chevron 87 grade fuel, added a bottle of Chevron fuel injector cleaner, and bumped my tire inflation up to 36 psi (was around 31)... I filled up this morning after driving 355 miles and it took just over 10 gallons, so these small changes increased my mileage by almost 5 mpg. I realize this is only one tank but I'm optimistic that the increased efficiency will last.

I have an 06 manual CE... I drive it 20 miles each way to work at least 6 times a week and it's about 50% interstate and 50% city streets.... I had been averaging about 30-31 MPG.... This last tank I used Chevron 87 grade fuel, added a bottle of Chevron fuel injector cleaner, and bumped my tire inflation up to 36 psi (was around 31)... I filled up this morning after driving 355 miles and it took just over 10 gallons, so these small changes increased my mileage by almost 5 mpg. I realize this is only one tank but I'm optimistic that the increased efficiency will last.

Why did you use fuel injector cleaner on a brand new car?

I have been getting only 25 - 27 MPG and I am driving 100 miles per day. I don't think that is very good. I have the 1.8L 7A-FE engine and I really like the power that it has. My wife's car has the 1.6L 4A-FE engine and would probably get better mileage. Maybe we can trade??

Why did you use fuel injector cleaner on a brand new car?

 

That's a good question.... Although it is a 2006, I've already managed to put nearly 10,000 miles on my vehicle and have been guilty of purchasing gas that may not have been of the highest quality. Therefore, I used a bottle of injector cleaner to remove any build-up that may have occured to date...

 

Why did you use fuel injector cleaner on a brand new car?

 

That's a good question.... Although it is a 2006, I've already managed to put nearly 10,000 miles on my vehicle and have been guilty of purchasing gas that may not have been of the highest quality. Therefore, I used a bottle of injector cleaner to remove any build-up that may have occured to date...

You must drive a lot to have put on 10,000 miles already.

 

 

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one Still, I can't be entirely sure yet.

 

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

You have Denso. Delco starts with P/N 89666, Denso starts with 89661.

What's your MPG?

AT or MT?

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one

Still, I can't be entirely sure yet.

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

You have Denso. Delco starts with P/N 89666, Denso starts with 89661.

What's your MPG?

AT or MT?

All mine are Denso and start with 89661-.

 

 

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one

Still, I can't be entirely sure yet.

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

You have Denso. Delco starts with P/N 89666, Denso starts with 89661.

What's your MPG?

AT or MT?

Wow, you just refuted the ecu hypothesis.. thanks for the info. I have auto and I get around 24~25 mpg, half city half highway. Hmm maybe its the gas thats causing worse gas mileage, but the thing is I tried different brand/grade gas and I consistently get low mpg- maybe it has to do more with the region that I live (north east, maryland)

Ok, I tried checking my ECU this evening by removing my glove box compartment. I did locate the ECU, but I could not identify whether it is made from Denso or Delco. It didnt say on the visible part of the unit, so this weekend im going to literally take off the ECU and check it out that way. To tell you the truth, By comparing what I saw with the picture from the repair manual, mine looks like the delco one

Still, I can't be entirely sure yet.

I took some pics too

This is with the glove compartment removed The white "Toyota Denso 5"sticker is for the cabin fan, not the ecu.

My pos camera couldnt focus.. this is supposed to be the ECU located near the bottom

This is underneath the ECU, all it says is "Toyota Computer, engine control" and some numbers.

You have Denso. Delco starts with P/N 89666, Denso starts with 89661.

What's your MPG?

AT or MT?

Wow, you just refuted the ecu hypothesis.. thanks for the info. I have auto and I get around 24~25 mpg, half city half highway. Hmm maybe its the gas thats causing worse gas mileage, but the thing is I tried different brand/grade gas and I consistently get low mpg- maybe it has to do more with the region that I live (north east, maryland)

I also have auto and am currently getting 29.6 MPG doing almost all highway.