Fuel Efficiency and the Yaris

[BailOut]

Originally Posted by Smokey159

If you're calling me a liar, I'll give you the short log I have. I'm not as anal about keeping logs as you are I'm sure. I can tell you that only the exact same trips were performed in my before and after trips, if I had to deviate, I took my truck. The comparisons consisted of 200 miles each, with a 60-40 combination of highway and city driving respectively. Temps were anywhere between 60 and 75 degrees.

You're not a liar, you're just presenting results from completely inadequate testing as solid data. This is what got you into trouble the first time and why my heart sank the second that I saw your new post on a stickied thread.

In order for MPG results to be trusted we will need to see at least 3 full tanks of similar driving conditions both before and after a CAI installation, and it is prudent to also include 3 more after taking the CAI back out if time permits. Including standard MPG tracking data such as distance driven, amount of fuel filled, average daily temperatures (not guessed at but culled from weather services), etc. are also needed in order to gain a more clear picture of the testing.

Please perform this testing before continuing any further with your presentation.

[bigjimmysrock]

i think you need at least 5 tanks!

[BailOut]

Outstanding, Voodoo! You have definitely raised the bar, and I bet you had a blast doing it.

[BailOut]

Well done, voodoo! That's a new single tank MPG record!

[metalshark]

Hate to ask again but don't they sell imperial gallons in Canada?

[Jister]

Very nice thread,
Yesterday was my first driving the yaris for longer distance - about 500km (~300 miles)
fuel consumption for the first 250km (150 miles) was - 9.5 l/100km (24.7 mpg)
for speeds between 120 - 140 kmph (75-87 mph) plus one time testing top speed - to 200 kmph (125 mph)

for the other 250 km (150 miles) my foot was very light :) just trying to keep constant speed - FC was 7.6 L/100km (31mpg) for speed between 100 -120 kmph (62 -75 mph)

the test was made on the highway with 2-3 stops for a rest
there was 3 people in the car all the time
the Car is yaris TS 2008 - 1.8L dual VVT-i

my next target is to try some road with maximum speed of 90 kmph (~56mph) and using DFCO - If I manage to make 5.9L/100 km (40mpg) with this engine - WOW! :)
Of course it cannot be compared to my motorcycle FC :) with full throtle open every time that is possible and speeds around 150 - 180+ kmph (93 - 112+ mph) FC is no more than 6.5 - 7 L/100km (36 - 33 mpg) it's the ultimate green peace machine :)

[BailOut]

Hello Darrin,

It is likely your driving style that is hurting your mileage. Please read through the first few posts in this thread and then try adjusting some of your habits accordingly. Let us know if no MPG improvement occurs.

[mchllp925]

Thanks! I read your earlier posts and will definitely impliment many of those points. Up here in Winnipeg our winters are harsh ( 2-3 months of -20 to -40 celsuis temps) so I will need to idle for at least 30 secs to ensure oil movement to the heads before moving.
Taking out the spare will help save gas? I will try that ( only thing in there)I was not aware of the DFCO so I will be looking for that.

So I will respond later with hopefully a better mpg.
Thank you again for the tips!
Darrin

[mchllp925]

Hi, me again, Just went to get the morning paper and I tried to keep the acceleration 2,000 rpm or lower. WOW I really am a lead foot. It took a little concentration to do that, usually got to the speed limit as quick as I could.
Ho boy can I see the fuel savings.
Darrin

[orheen]

For the fuel consumtion of yaris 1.0 your speed must be at 65 km/h when only driver in the car. When you 5 people your speed must be 100 km/h

yaris 1.3 best fuel comsumption speed 78 km/h

yaris 1.4 d-4d manuel 78 km/h

yaris 1.4 d-4d multimode 68 km/h

I will put the diagrams here that show speed - strenght. And fuel consumptions.

[marcus]

wow......great lookin graph.. good job..atleast ur stats are more realistic..very close to mine...i just dont get how people getting 800km on a 37 liters...i think ill get bored hypermilling the whole time..

your dec 11th 2008 was a little weird seems not possible unless you kept ur engine running in neutral for a very long time.. plus it shows hwy.. you going 180km/hr the whole time??

[knowmercy]

You know, this article is an absolutely great resource! I'd like to offer some, hopefully insightful information to it. Some of these suggestions do make your car use less gasoline, however they can substantially wear on other parts of the vehicle. For instance, shifting at 2k rpms will almost certainly lug the motor and the risk of detonation is considerably higher at rpms that low. The second thing about that is you actually burn less fuel depending on the engine load at the time. So shifting at 2500 or 3k under light load burns about the same amount of fuel as shifting at 2k under moderate load or heavy load. You press on the gas harder, more air comes in and the engine puts more fuel in there. Also, turning off the engine at lights is horrible for it. Every time you restart the engine it takes a short period of time to rebuild a "safe" amount of oil pressure in the engine. This is not achieved if you start the engine and drive off. Not to mention the wear on the starter, relays, and fuel pump. Not trying to be a downer on any of the resources that have been made available. Making a car use less fuel doesn't equate into the best health for the car. Also, always running your car at low rpms actually creates a TON more carbon build up inside the engine. I hope this is helpful to folks who are trying to not only save fuel, but keep their car running for a long time. :)

[BailOut]

Welcome to the forum, knowmercy. I know you meant well with your post and I appreciate that, but I disagree with most of what you presented.

Originally Posted by knowmercy

For instance, shifting at 2k rpms will almost certainly lug the motor and the risk of detonation is considerably higher at rpms that low.

The ECU adjusts for this by retarding the ignition timing by quite a bit. I have never heard any audible indicators of pre-detonation.

Originally Posted by knowmercy

The second thing about that is you actually burn less fuel depending on the engine load at the time. So shifting at 2500 or 3k under light load burns about the same amount of fuel as shifting at 2k under moderate load or heavy load. You press on the gas harder, more air comes in and the engine puts more fuel in there.

The fuel/air map in modern engines is anything but linear, and using a simple tool like a ScanGauge shows that what you say here is just not the case. The loads do not always occur where you think they do.

Originally Posted by knowmercy

Also, turning off the engine at lights is horrible for it. Every time you restart the engine it takes a short period of time to rebuild a "safe" amount of oil pressure in the engine. This is not achieved if you start the engine and drive off.

While it is easy to believe statements like this they simply are not true. Oil pressure has nothing at all to do with the current coverage of oil on any part of the engine. Pressure only lifts oil from the pan to the top of the block where it begins a gravity-fed trip back to the pan. Oil does not magically disappear from all internals the second you turn off the ignition.

Originally Posted by knowmercy

Not to mention the wear on the starter, relays, and fuel pump.

As is mentioned in the first posts in this thread, the break even time for idling versus all wear and tear on a modern vehicle is just 7 seconds. If you can't wrap your head around that number then allow me to show you a real world example:

Even with the carpoolers, equipment, snow, elevation and climbs I deal with I still average about 46 MPG. I think we can all agree that the median MPG for all Yaris owners is 32 MPG. I drive roughly 17,000 miles per year. At 46 MPG I use 370 gallons of fuel. Someone at 32 MPG uses 531 gallons to go the same distance. With fuel at $2.50/gallon I will spend $925 on fuel for the year while the 32 MPG-er will spend $1,328. This means I save $403 per year in fuel costs.

To put that into perspective a starter replacement costs about $180 and comes with a lifetime warranty (I am at 37k miles and still on the OEM starter despite using it more than a dozen times per day). A replacement fuel pump costs about the same (I am still on the OEM). Relays are all less than $20 (I am still on the OEM).

In other words, even if I had to replace one of those items every year I would still come out way ahead.

Originally Posted by knowmercy

Also, always running your car at low rpms actually creates a TON more carbon build up inside the engine.

This is inaccurate. Carbon buildup occurs due to incomplete combustion and exhaust processes. This condition is rare in the Yaris due to the tight control the ECU exerts, and from posts in the tuner forums I would say that it is far more likely to occur at high RPM than low. It's not like I have torn down my engine but I see no signs of carbon or sludge anywhere that is easily accessible (none under the oil cap area, nothing in the throttle body, no fouled O2 sensors, etc.).


Again, I know you meant well, but spreading disinformation helps no one. In the future please be sure to research any information you have before sharing it, and never, ever be afraid to perform your own research.

[daf62757]

Just curious....when some of you get +50 MPG in your 1.5 Yaris, do you do anything special? What is your speed? Oil? Air Filter? Spark plugs? Tire pressure?

[knowmercy]

Thanks for replying to my comments. I appreciate the wealth of knowledge that you provide here. :) I've rebuilt many engines and I think we're going to have to agree to disagree on a few points, but that's ok. For what it's worth, I got about 31mpg on my first tank and I'm up to about 36 now with approximately 1100 miles logged now.

[vancouveryaris]

would changing to synthetic oil help with fuel efficiency?

[BailOut]

Originally Posted by vancouveryaris

would changing to synthetic oil help with fuel efficiency?

Hello there,

Yes, it does help with efficiency, but only by a small amount. That amount is often too small to break even with the higher cost of synthetics.

To get around the cost issue I run an extended performance synthetic with a 15k mile drain interval.

In the big picture there are many other benefits to running synthetic motor oil such as better protection during cold starts, better resistance to thermal breakdown, etc. In the end each of us needs to make our own decision and decide on our own price point.

[BailOut]

Well done, voodoo22! Pulling 50+ MPG in Winter is no easy feat at all.