23 mpg...really???

[Yury]

Everyone here seems to talk about how great a mileage they get, but how about this: my last tank was 23 mpg. What the...?

A tank just before was 29.5. Not stellar either, but 23 is ridiculous.
It's a 08 auto with low mileage and no problems whatsoever. TB cleaned a couple of weeks ago, MAF is clean, tires are properly inflated, injectors cleaned off car just this winter. Driving style: grandpa.

99% city, often with wife and two small kids and AC on 100% because it's been very hot and humid. I understand it's going to affect the mileage, but 23...how are you guys getting high 30s in all city driving? My personal best is 34 when I was driving mostly highway.

I am tempted to get the at fluid changed even though it's far from due. Other than that I just don't know anymore..

[edmscan]

Where in Canada do you live ? Calgary ... the drivers there are terrible. :thumbup: But I would tend to agree .. that does sound like something is not quite right. Are you sure you are calculating it right ? How many KM are you getting in a tankful ?

[fnkngrv]

I would usually lose about 3mpg with the AC cranked 100% and using it constantly as a point of reference. I am not saying that the 23/24mpg is acceptable for city, just giving you a point of reference. Perhaps an ECU reset by disco the battery for 30 minutes or so to make it relearn your long term fuel trim may help? Other than that have a scangauge connected to see what is happening during load.

[WeeYari]

It can happen. I've gotten very close to that low myself.

Since you haven't stated where in Canada you are I'm going to assume your weather conditions are what I've been experiencing this past month. Constant >30c heat.

At these temps, the air is very thin and combustion can be air starved resulting in less efficiency. Combine that with 100% A/C, 99% city, and often a full passenger load and you will suffer. This engine hates A/C (and weight).

Most of the people touting high mpgs are not running constant A/C, and are almost always the single occupant of the vehicle.

My last fillup, yesterday, saw 27.85 mpg. That was mostly city, with very little use of the A/C.

Edit: Just check another thread. You are in the GTA and living the same conditions as me.

[caineroad]

OP please tell us how many KM you get for a full tank.

I dont know my mileage but I get about 430-460km (depends how hard i drive) then the last bar flashes.

Also the stupid ethanol contributes to our fuel mileage too,

[Yury]

Where in Canada do you live ? Calgary ... the drivers there are terrible. :thumbup: But I would tend to agree .. that does sound like something is not quite right. Are you sure you are calculating it right ? How many KM are you getting in a tankful ?

Toronto. I reset the trip A on fill up and on the next fill up divide the liters I put in by the amount of km on the trip A.

This time around I went to 2 bars and if I remember correctly the trip was 270 or so...the number of liters that I put in was about the same as km traveled. Normally I go by half-tanks and on bad fillups like this it is around 210 km. On better fillups I get maybe 250.

The drivers here are pretty average. I almost never have to brake hard.

[Yury]

I would usually lose about 3mpg with the AC cranked 100% and using it constantly as a point of reference. I am not saying that the 23/24mpg is acceptable for city, just giving you a point of reference. Perhaps an ECU reset by disco the battery for 30 minutes or so to make it relearn your long term fuel trim may help? Other than that have a scangauge connected to see what is happening during load.

the fuel trims are about usual. small single digits under load and about -4 idling. I have seen these numbers in winter too. In my experience if I disconnect the battery long term trims are zeroed but go back within like an hour of driving. I can try, but I don't have much hope.

Btw, no need to keep it disconnected for 30 min. I tried disconnecting for a few minutes and it got the long term trims zeroed just fine.

[Yury]

It can happen. I've gotten very close to that low myself.

Since you haven't stated where in Canada you are I'm going to assume your weather conditions are what I've been experiencing this past month. Constant >30c heat.

At these temps, the air is very thin and combustion can be air starved resulting in less efficiency. Combine that with 100% A/C, 99% city, and often a full passenger load and you will suffer. This engine hates A/C (and weight).

Most of the people touting high mpgs are not running constant A/C, and are almost always the single occupant of the vehicle.

My last fillup, yesterday, saw 27.85 mpg. That was mostly city, with very little use of the A/C.

Edit: Just check another thread. You are in the GTA and living the same conditions as me.

What I don't get is how different fillups can be with no significant changes in weather. It's been hot summer so far and I get deviations of 5 mpg between subsequent fillups.

EDIT: which tread are you referring to?

[WeeYari]

EDIT: which tread are you referring to?

The List of GTA Members thread in which you indicated Thornhill.

[vten]

Bad O2 sensor perhaps ?

I have 08 Yaris HB , 30xxx mi on the odo, supercharged with aftermarket adds on. 17" wheels and Use a/c all the time and still getting 33-36 mpg..... That's with an O2 sensor CEL code tho ... (ordered the new part n waiting to arrive)

[fnkngrv]

going on half tanks or other partials can be very subjective. with how much the fuel moves around in the tank I have personally experienced divations anywhere from 5-20 miles on the OD and have tested by actually refilling after 2,3, & 4 bars down. Add in the heat/humidy indices and it can really wreak havoc on FE. I had a couple tanks while in Memphis in 08 and then again in central AL last summer that were very similar to your experience during the dog days of summer. I also had a few tanks the last couple winters where I avg around 22/23 as well. It sucks, but it can happen.

[Yury]

The List of GTA Members thread in which you indicated Thornhill.

Oh that. I misunderstood you. Yes, I am at the very south part of Thornhill.

[Yury]

going on half tanks or other partials can be very subjective. with how much the fuel moves around in the tank I have personally experienced divations anywhere from 5-20 miles on the OD and have tested by actually refilling after 2,3, & 4 bars down. Add in the heat/humidy indices and it can really wreak havoc on FE. I had a couple tanks while in Memphis in 08 and then again in central AL last summer that were very similar to your experience during the dog days of summer. I also had a few tanks the last couple winters where I avg around 22/23 as well. It sucks, but it can happen.

I am only using bars as a rough indication and do the math after each fill up.

[WeeYari]

Oh that. I misunderstood you. Yes, I am at the very south part of Thornhill.

Yeah, I meant to say 'checked'.

[Yury]

Bad O2 sensor perhaps ?

I have 08 Yaris HB , 30xxx mi on the odo, supercharged with aftermarket adds on. 17" wheels and Use a/c all the time and still getting 33-36 mpg..... That's with an O2 sensor CEL code tho ... (ordered the new part n waiting to arrive)

If the lambda sensor was off I imagine I'd see funny long term fuel trim numbers due to discrepancy between lambda and MAF sensors.

[WeeYari]

At this point I'd say just sit and monitor for a while. Do more frequent smaller fillups so that you can do the math against a narrow list of environmental and physical variables.

[tooter]

Everyone here seems to talk about how great a mileage they get, but how about this: my last tank was 23 mpg. What the...?

A tank just before was 29.5. Not stellar either, but 23 is ridiculous.
It's a 08 auto with low mileage and no problems whatsoever. TB cleaned a couple of weeks ago, MAF is clean, tires are properly inflated, injectors cleaned off car just this winter. Driving style: grandpa.

99% city, often with wife and two small kids and AC on 100% because it's been very hot and humid. I understand it's going to affect the mileage, but 23...how are you guys getting high 30s in all city driving? My personal best is 34 when I was driving mostly highway.

I am tempted to get the at fluid changed even though it's far from due. Other than that I just don't know anymore..

Have you tried installing a new air filter?

Really humid air could be moisturizing the dirt on the filter and make it "pack" into the filter fibers and clog the filter reducing air flow and decreasing gas mileage. I've seen that happen on the return air filters of home central heat/cool systems.

[Yury]

^ the filter is only a couple months old.

Besides, I've been led to believe that in FE vehicles a dirty filter degrades power, not mileage. Fuel injection will compensate the injector pulse to keep the mixture stoich, i.e. with less air it'd inject less fuel. So, I'd imagine the net result would be the same as less throttle.

[tooter]

^ the filter is only a couple months old.

Besides, I've been led to believe that in FE vehicles a dirty filter degrades power, not mileage.

With less power you'd be stepping harder on the gas pedal and I'd think that the mileage would decrease. But I could be wrong... I often am. :wink:

[xnamerxx]

The only thing I've noticed that really kills fuel economy in these cars is driving to fast ie faster than 75 mph. I've done a few sub 26 mpg tanks but it's always been from driving 90+ mph for long stretches of driving. Being the car has 30k miles on it I doubt anything mechanical or electrical is wrong with the car a bad filter can reduce mileage but you would need a crazy blockage in flow for it to be bad. I'm willing to bet its due to driving style ie flooring it driving through traffic or crusing at 85 mpg on the freeway or having to drive through the mountains things like that.

[WeeYari]

You are way off the mark xnamerxx

Driving style: grandpa.

plus there aren't any mountains where the OP lives. Hell, there are hardly any hills.

[Yury]

You are way off the mark xnamerxx



plus there aren't any mountains where the OP lives. Hell, there are hardly any hills.

and I am not on the highway often.

But generally it's a good point.

[Kaotic Lazagna]

The second I hit the AC button, I'm losing 10mpg. I can see this on my SGII.

[edmscan]

Toronto. I reset the trip A on fill up and on the next fill up divide the liters I put in by the amount of km on the trip A.


So to get 23.52 MPG (I trust you are using US MPG). You would need 10 L/100 KM .... which would give you about 375 KM for a tankful / assuming 37.5 Litres for a FILL.

I know this may be boring .... but there are websites like www.Fuelly.com which will make this much easier for you. You only have to enter your KM and LITRES .. and it will calculate your mileage for you. It will allow you to use L/100 Km or Imperial MPG or US MPG whatever your preference is. Have fun.

[Yury]

^ it's not hard without fuelly.com...just a quick calculation before I pull away from the station which I do every time. And I do operate in L/100 km, I only convert to US mpg when I post here so it's easy for the majority of folks on this site.

10L/100km is exactly what I got last time and about 8 before that.
Imperial MPG is basically an irrelevant unit...

[zkay]

The second I hit the AC button, I'm losing 10mpg. I can see this on my SGII.

Not to threadjack, but how can this be?

My wife and I recently took a trip to wisconsin from northeast iowa on I-80 and we had the A/C cranked the entire time (100% cool, set to recycle cabin air rather than cool outside air) and at "3" on the dial and we still got 46.5mpg. It was hot, humid, and there was some medium traffic at several points; never slowing down past 45mph.

I was doing 65-70mph all the way there and back besides the slow areas I mentioned, and not really trying to hypermile. We are also not small people, if there's any delicate way to put it.

I don't understand the huge variances seen here, if only because I generally have gotten a very reliable (and smallish) F/E range with my yaris.

[Yury]

^ is that by calculation after a fill up?

[zkay]

^ is that by calculation after a fill up?

I don't usually do the math myself, but have. I generally just get a receipt at the pump and put the information into fuelly. The times I have done the math myself, it's always within .01 of what fuelly gives me back.

[Yury]

that's ok, I just wanted to make sure it's not based on obd data.

I dunno, 45mpg=5.22 L/100 km with 2 adults in a car and ac. I dunno...I never got more than 34 mpg from this car even when I was doing highway commute. Nowdays, with all city my average realistic mileage is around 28 mpg summer and winter. There's a window of couple of months late spring/early summer when it's not to hot and humid and then I might get 31.
All maintenance is very up to date.

On the other hand my mom's Mazda 5's last tank was 18 mpg. She is also all city, very similar driving patterns, but no occupants and a heavier foot than me. In colder and less humid summer weather she gets about 21.

[Kaotic Lazagna]

Not to threadjack, but how can this be?

My wife and I recently took a trip to wisconsin from northeast iowa on I-80 and we had the A/C cranked the entire time (100% cool, set to recycle cabin air rather than cool outside air) and at "3" on the dial and we still got 46.5mpg. It was hot, humid, and there was some medium traffic at several points; never slowing down past 45mph.

I was doing 65-70mph all the way there and back besides the slow areas I mentioned, and not really trying to hypermile. We are also not small people, if there's any delicate way to put it.

I don't understand the huge variances seen here, if only because I generally have gotten a very reliable (and smallish) F/E range with my yaris.

No clue. But here's another kicker, just did a trip with the AC on and was averaging ~45mpg. So now it's changed, I'm getting better gas mileage with the AC on than it off since when I drove back home that night (without AC on), I was averaging 40mpg. :iono:

[nookandcrannycar]

The only thing I've noticed that really kills fuel economy in these cars is driving to fast ie faster than 75 mph. I've done a few sub 26 mpg tanks but it's always been from driving 90+ mph for long stretches of driving. Being the car has 30k miles on it I doubt anything mechanical or electrical is wrong with the car a bad filter can reduce mileage but you would need a crazy blockage in flow for it to be bad. I'm willing to bet its due to driving style ie flooring it driving through traffic or crusing at 85 mpg on the freeway or having to drive through the mountains things like that.

^^^^^ This + wind. My worst overall tank (a bit over 32 mpg) = eastbound on I-10 in Texas on the 80 MPH limit part (between mile marker 62 and mile marker 494) with a strong crosswind to boot.

[Yury]

Weather cooled down, ac is now used significantly less. 27 mpg this time. Better, but still not great. I used to get about that mileage during last winter and same driving patterns.

[Kaotic Lazagna]

Are you using cheap gas, and is it possible that the gas station you're filling up in is still, some how, using winter blend gas (worse gas mileage with winter blend, even worse if using cheap gas).

[Yury]

^ highly unlikely. I use Petro Canada which is one of the major brands around here.
I am not even sure you can get 'cheap gas' around here, it's all major brands everywhere.

[goliath1812]

Maybe try switching to Shell if there's one close by for a couple of tanks, see if that helps..I haven't really heard many good things about Petro, other than Petro Points. lol.

Also, you said tires are inflated properly...try taking them up to around 40 if you feel comfortable. I've been running between 40-44 on all 4 tires with good results.

[Kaotic Lazagna]

Not really sure then. Check your wheel alignment and increase your tire psi. I'm constantly running at 49-51 COLD psi without a problem (sidewall tire psi rating is for cold psi, I believe).

[Yury]

alignment is in green..the rear right toe is real close to the limit (still green though)...Don't like over-inflating, the ride is too harsh as is.

[Red Horse]

maybe your driving in 3rd gear

[edmscan]

maybe your driving in 3rd gear

I found a HUGE increase in gas mileage just by not driving in 3rd gear .. I now drive in 4th gear when possible and find that my mileage has improved. According to my ScanGauge I have been able to get up to 54 MPG (4.3 L/100 KM) just by doing this small change. However my ACTUAL gas mileage is more like 43 MPG (5.5 L/100 KM) when I fill up. :w00t:

I drive a standard shift .... so for automatics this isn't an issue.

[Yury]

maybe your driving in 3rd gear

well, how should I put it...a big letter D staring me right in the face is kinda hard to miss :D
and, oh, yeah, it's an auto :D

[charles nelson]

I bet most of us could drop our mileage that low by buying the highest ethanol content gas, hauling max loads, and hard fast starts at every intersection with constant heavy traffic slowing and then speeding up. In that case...I would think about getting the new Prius with regenerative braking. The gas saving would eventually pay for the premium to buy a Prius on a Yaris chassis.

[Lux]

There must be something going awry with your calculations to produce 23 milers per American gallon. I would not use half-tanks as reference. Unless you have a voltmeter directly to the fuel level sender, half tank on the gauge is always interpretive.

I also live in Toronto and I get 600 - 650 km per tank, city only, air conditioning periodically used. City driving is usually where the Yaris should be faring better. Is your gearbox shifting late? It may need a relearn.
Are you using cheap gas, and is it possible that the gas station you're filling up in is still, some how, using winter blend gas (worse gas mileage with winter blend, even worse if using cheap gas).
All brands of petrol stations are supplied by the same handful of refineries.