Fuel Efficiency and the Yaris

[BailOut]

Hi CheapYarisOwner,

There's not much to the solar trickle charger other than the link I gave in the "FE Mods" section: Long Link

... and that you have to drill a small hole in the firewall in order to mount it directly to the 12V battery. I just matched a drill bit to the cable's size and drilled it just to the right of the heater hose. You can't plug it into the 12V adapter inside the cabin as it puts out just enough power to initialize the entire chassis side of the ECU, which uses more juice than the panel provides, thereby creating a drain.

I also had to use a small round file on the back corner of the area of the dash that's right in front of the gauges in order to make the cord lay the right way and not be pinched.

It's not a miracle device, producing just 200mA at 12.3V in direct sunlight, but it accomplishes two things:

1) It replenishes the missing electricity from your battery that was a deficit when you parked it. I have a good climb right before I get to my office and my voltage readout usually shows 12.4V - 12.6V as I park. A full battery in the Yaris usually reads ~12.8V.

2) Once your battery is topped off it keeps it topped off, ensuring that 100% of the battery is available to you at the next start.


These things mean that you'll never have a dead battery (unless a major failure occurs) and when you start up your alternator doesn't have to engage for so long because all it's making up for is the energy used to turn the starter, rather than that plus all the juice you bled off during the down time. The less the alternator places a load on the engine the less fuel your engine needs to burn.

In real-world usage I've found that this solar trickle charger gets me back up to 12.8V in about 2 hours in good light (roughly 1/100 of a Volt every 3 minutes). On a cloudy day it can take up to 6 hours. Of the 2 parking garages I've been in things were odd because one was open to the outside but it was night when I was there, and the other was underground but very well lit, so much so that it still charged about the same as a cloudy day.

[Maypo]

Thanks, BailOut, for a fabulous amount of useful information; and other responders for adding ideas and opinions. I am going to try some of the new 'tricks' for myself.

A few comments on what I read here:

1) From BailOut's original list of hypermileage suggestions the one I am skeptical about is the "slow acceleration" gambit. Years ago, BMW did some testing to determine the optimum throttle-position and rpm shift-point for fuel efficiency. They tested all the combinations of 1/3 and 2/3 throttle-positions, with 3000 and 5000 rpm shift-points, and concluded that low rpm (3000), combined with heavy throttle (2/3) application was most efficient. Also, during the years of the famous Mobil Economy Run, it was discovered that the best methodology for fuel efficiency was full-throttle acceleration to some predetermined speed, followed by coasting. Anyway, I have not heard or read anything to the effect that BMW 's conclusion has been superseded by newer technology.

2) BailOut bemoans the ending of the 55 mph NSL (National Speed Limit), but most of us do not. While limiting the entire populace to an artificial maximum speed saves fuel, it wastes a truly non-renewal resource: time. Also -- in retrospect -- it has been shown that highways were less safe, when the speed limit was established based on politics, instead of engineering principles (not a surprise, actually).

As an aside: Back when the draconian NSL was in effect, myself and several friends conducted our own 'fuel economy vs. speed' testing, by fitting a fuel meter to the gas-line on one of our Fiat X1/9s and driving up and down I5 at varying speeds to chart a fuel-use curve. We discovered that our peak fuel economy was achieved @ 75 mph (39mpg), and the 33 mpg we recorded @ 55mph was duplicated @ 85mph. Thus, the Federal Government was costing us time and fuel.

Although technology has pretty much locked fuel efficiency to standard highway speeds, I suspect there are still vehicles whose fuel economy is little affected by 'keeping it to 60.' In fact, my previous car, a Nissan 350Z, got 33 mpg @ 60 and 30 @ 70 -- a trade-off I was happy to make.

3) Some of the comments in this thread are about modeling better driving behaviors, and I am all for that. (I have a personal program of turning my headlights off when I am stopped at a red light and facing oncoming traffic, i.e., in a left-turn lane, as a courtesy. After 6 years of this, I have been rewarded by like treatment exactly twice, so, this project won't be ending anytime soon.) However, driving slower than prevailing traffic to 'control traffic,' or feel good about saving petroleum is not the kind of behavior I would want to model, nor is it likely to have a net benefit in the moment. Minimum overall fuel is consumed when speed changes in traffic flow are minimized. At the sane time, safety is enhanced and stress is reduced. All of which is why -- as far as being socially-responsible behind the wheel goes -- I recommend behaviors that facilitate traffic flow. (Even the Defense Driving that is hammered into us falls short, in regard to efficiency.) And, while that includes al lot of the ideas and suggestions already mentioned here, it doesn't include forcing others to slow down below prevailing speed.

Happy motoring!

[Smokey159]

Quote:
Originally Posted by Yaris Newbie
Will a cold air intake improve MPG?

Only if you drive like a testosterone-infested aggressive punk.

LOL, horrible answer.

Before the hack, I did an extensive report on Simota's Carbon Charger... should've saved it.

But anyways, I got an increase in MPG of 1.5MPG. After doing the math, at $3 a gallon, it would take around a year and a half to pay off the investment of the intake. (this number obviously depends on how much you drive per year and the actual price of gas).

Only the "testosterone-infested aggressive punks" LOSE mileage because they want to hear the new sound the intake makes since you can only hear it when you apply more throttle.

Before someone tries to tell me I'm wrong, let me explain. Also keep in mind that I have been an engine builder for almost ten years and I am Dynojet certified to operate their Dynomometers and administer their Power Commander engine management systems.

OK, simply put, if you make an engine more efficient, you save gas. I'll preface this by saying YOU CANNOT CHANGE YOUR DRIVING TECHNIQUES and keep this statement true at the same time.

When you hear people say: "If you introduce more air to an engine, the ECU adds more fuel, making it less fuel efficient" you may tell them that they are HALF right. The fuel mapping DOES introduce more fuel, however this is to keep the air/fuel ratio correct (usually aroun 14:1). Now here is where they are wrong, if you introduce MORE air and MORE fuel to a motor, you make it more powerful, AND more efficient.

If a motor has more power, you don't have to press on the pedal as hard. Opening the throttle less will ALWAYS use less gas then the ECU has added to balance the ratio. As a result, you get better fuel mileage. Think about it this way, with the same amount of pedal, you go further.

Done deal, stop arguing about it. Buy an inexpensive intake and follow the following rules:

1) Reset the ECU after the install by disconnecting the battery for a few minutes, then reconnect it and start the motor. DO NOT REV THE ENGINE, just let it idle for about 5 minutes and then shut it off.

2)Don't buy a high priced intake, this will only make it harder to pay off. CAI are usually higher priced than SRI, but they offer little more in terms of engine efficiency in the real world.

3)Make sure that the design of the intake does not place the Air Intake Sensor too close to the throttle body, this will actually make the engine run rich. for example: Simota's carbon charger is as close as you want to get.

4) Do not change your driving habits, you will see a reduction in fuel economy if you want to hear it. This is harder than you think, it does sound cool.

This is not a smack down post, I just want to clear this up because many people don't truly understand some of the concepts.

[BailOut]

Smokey159,

While I appreciate you taking the time to work this up I have a few issues with your findings.

My primary issue is your claim of 1.5 more MPG. You show no mileage logs, offer no data points such as the length of your testing both before and after the installation, ambient temperatures during testing, the condition of the OEM filter before you swapped it out, etc. Please quantify your results.

Secondly, you neglected to mention how intakes perform differently at varying altitudes. As you are in Kentucky are we to infer that all your testing was done near sea level? Did you test at any other altitudes?

[Smokey159]

Altitude? 1500 feet.

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.

My car had less than 5000 miles on it when I did the change, so the stock air cleaner looked practically new. I still have it if you want a pic.

Does 1.5 MPG sound like a lot to you? Personally I was a little disappointed. Quantifying my results to your standards is not necessary for me to find out whether it helped my MPG. I tried to keep as many variables constant as possible while keeping it a real world scenario. I have no interest in whether or not people are skeptical to my findings because I am not here to sway anyone. The facts and physics of internal combustion engines in today's vehicles have been proven enough, it is an ancient technology.

The fact of the matter still remains no matter if my testing had flaws or not. A properly designed(*key point) intake that increases airflow will allow the engine to operate at a higher performance level(also assuming the ECU can still manage a good air/fuel ratio). This has been proven time and time again by dynomometers. However, I will say that there is a point in performance gains where it is necessary to add more fuel than normal which leads to a loss in MPG, but this scenario is WELL beyond a simple intake modification.

Again, more power leads to an overall more efficient vehicle, keeping all other things constant, including driving habits. I'm sure you've noticed how much gas can be wasted by just the smallest increase in throttle. I believe I read something you wrote about exploiting fuel mapping(which I completely believe) that falls closely with what I'm talking about. Increasing the performance of a 4 stroke engine allows you to ride in fuel mapping areas for lower throttle positions, thus saving fuel.

Bailout, I understand that you have a different opinion about these sorts of things, and I'm fine with that. I don't expect you to change your opinion just on my words, you're too set in your ways to let a post influence your beliefs(that's not meant to be an insult). However, there are people out there that will look at your views, and look at mine, and decide how they feel about it. I'm only out to share my own experince with people.

That being said, I won't add to this thread anymore, and let others create their own beliefs. I absolutely will not get into a "back and forth" with anyone.

[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!

[Mikeb Yaris]

[BailOut]

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

[marcus]

Originally Posted by voodoo22

Got 47.5 US MPG on the last tank with multiple trips to the heart of downtown Toronto and several excruciating traffic jams. That ends the 50+ US MPG streak. I'm halfway through the current tank and while it's looking a little better, I don't believe I'll touch 50 US MPG on it either. The cold weather and snow may have put my ability to break that barrier on the shelf until next spring.

Started May 29th
Ended October 7th
Number of tanks: 11
Distance traveled 9359.71 kms 5815.85 miles
Gas used: 420.688 litres 109.37 gallons
Average FE per tank 4.49 l/100km 52.31 MPG
Actual FE for the streak 4.49 l/100km 52.31 MPG

still dont know how ur doin this.. i have drove 90% hwy during camping no traffics going 90km /hr no aggressive acceleration.. and the most i got on a 36liter is 685km.. whats your secret... i believe i did 44 or 45 m/gal

[romeroalfred]

Hey there guys and gals just wanted to ask if any of ya'll place the automatic yaris on neutral when ya come to stops to allow the car to coast. I usually only drive in the city og Chicago and I wager I average 28 maybe 29 mpg. I would like to hear what ya think?
Alfred

[Mikeb Yaris]

Originally Posted by romeroalfred

Hey there guys and gals just wanted to ask if any of ya'll place the automatic yaris on neutral when ya come to stops to allow the car to coast. I usually only drive in the city og Chicago and I wager I average 28 maybe 29 mpg. I would like to hear what ya think?
Alfred

Coasting in neutral to a stop is not as efficient as simply letting the engine brake the car. See the sticky on DFCO. Simply put, the computer cuts fuel flow entirely down to about 1100 rpms, using no fuel at all. Coasting in neutral puts the car in idle and continues to consume fuel.

I usually use this feature and take it one step further by watching the tach and when it approaches 1100 rpm I click the transmission out of D and into 3 to keep the rpm's in the range where fuel is not burned. Then, when at the light, I pop it up into neutral so as to idle without a load on the engine. I use this same technique when making a right turn when I have a green light or traffic is clear for a rolling stop - just remember to pop the tranny from 3 back up into D otherwise you'll wind up revving too high when you get back up to speed. The gated shifter makes these maneuvers particularly easy IMO. When I first bought my car, the gated shifter seemed like a silly Euro gimmick, but I'm absolutely sold on it now!

[BailOut]

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

[marcus]

Originally Posted by voodoo22

A lot of whacky factors contributed to me getting my best tank of gas yet

Against:

cold morning weather
winter tires on

For:

only 2 short trips, the rest of the tank was all commute or highway driving on a shortish weekend trip which spanned just over 300 kms.
unusual blast of warm afternoon weather
no traffic jams
Oil change halfway through the tank where I got a new air filter

Somehow this combination equals

882.8 kms using 37.916 litres
4.29 l/100km
54.75mpg

I don't think I will be easily beat this mark. That shows how much of a difference those little trips make as in much better weather with all season tires, my previous best was 53.7mpg.

the most i do on 37liters is 600km if im lucky...

[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 :)

[mchllp925]

I now have 7,000 kms on my 08 Yaris and I am still only getting 10 km per litre or about 22 mpg. This is half of what Toyota has rated for this car.
My dealership says I should get better mileage when I have 15, 000kms.
Does this sound right?
Love the car but I expected better then this for mileage.
P.S. this is city driving

[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.