Fuel Economy

[foober]

Originally Posted by swng

Thanks a lot for the opinion. For the long term, I fill up the tank, set the trip odometer to zero, drive until the tank is quite empty(but I always try to leave a fuel reserve for about 100km in the tank), then fill up again, and record the trip odometer reading and the amount of fuel bought and then use those figures to calculate the fuel economy of the car. I do the same every time I fill up so that I can know how well my car does in the long term on average.
I believe many friends here use more or less the same method.

thats the method I use. I'll fill up after about half the bars are gone or 2/3 of the bars are gone. YOu just have to remember to redo the trip meter everytime you fill up.

[NickNickNick]

43.57mpg when I filled today. All city driving - very hard at times.

[swng]

Originally Posted by NickNickNick

43.57mpg when I filled today. All city driving - very hard at times.

Good number for all city driving! I guess you must be enjoying some warm weather and there may not be too many hills and traffic lights in your city hehe........You must have done something right anyway! I guess the gas companies won't like you.

[why?]

Originally Posted by Ziv

At the side of the car behind the door, it actually mention 32 PSI.

Is higher actually better? because I heard the higher it is, the greater chance of your tire can get bust.

Tires are created to withstand a certain air pressure. This is what is written on the tire.

Go by what is on the tire, not what the car says.

As long as you make sure to keep the pressure within those limits, then the higher up in that range you go, the better it is for gas mileage.

And while too much air pressure is a bad thing, there are rumors of some tires being overinflated too 100 psi, etc, and the tires not having a problem.

In general, if you try to overinflate a tire the air pump will blow long before the tire does.

[punch]

umm how do i do the math, I got 598Km on my first tank, it took 38l to fill it, whats the formula?? 598/ 38= 15.74km/l I then took 100km/15.74 and got 6.35

so if this is correct I got/used 6.35l per 100km, which is close to sticker epa ratings..

[Ziv]

Originally Posted by why?

Tires are created to withstand a certain air pressure. This is what is written on the tire.

Go by what is on the tire, not what the car says.

As long as you make sure to keep the pressure within those limits, then the higher up in that range you go, the better it is for gas mileage.

And while too much air pressure is a bad thing, there are rumors of some tires being overinflated too 100 psi, etc, and the tires not having a problem.

In general, if you try to overinflate a tire the air pump will blow long before the tire does.

Understood. Thanks for the advice, I will just do that.

One really stupid question tho, should all tire pressure to be the same to get best milage?

[Idjiit]

Originally Posted by Ziv

Understood. Thanks for the advice, I will just do that.

One really stupid question tho, should all tire pressure to be the same to get best milage?

No, typically people inflate the front tires between 3-5psi higher.

[Ziv]

Originally Posted by Idjiit

No, typically people inflate the front tires between 3-5psi higher.

Really? glad I asked. Then how should I match the tire pressure? if the tire said it's 32 let's say, and should I get the front up to 35ish?

[Idjiit]

Originally Posted by Ziv

Really? glad I asked. Then how should I match the tire pressure? if the tire said it's 32 let's say, and should I get the front up to 35ish?

If you want to follow the "max pressure" guidelines of the tire and the max is 35psi, then set the front to 35psi, and the rears to 32psi or so.

[Ziv]

Originally Posted by Idjiit

If you want to follow the "max pressure" guidelines of the tire and the max is 35psi, then set the front to 35psi, and the rears to 32psi or so.

Is that your current settings? Does anybody else find this best for fuel efficient?

[Idjiit]

Heh, I think mine are set ridiculously high right now because I didn't let air out after the rallycross I cranked them up for. :O

[Tankota]

Yes you might get some better milage by increasing your tire pressure above the factory recomended settings - but remember you will also increase uneven wear (the centers will wear out before the edges) your braking will be reduced and your corner grip will be reduced - plus the harshness of the ride will be increased... all cause by overinflating the tires.

The numbers on the door are a result of lots of testing with that size tire on that excact style of car - it's the pressure that gives you the best milage along with the best contact patch of rubber on the ground that size tire for that car. Reduce that, and you get less milage, more wear on the edges, and slop and roll on curves. Increase it, yes you might get some milage, but less rubber and control on the ground, harsh ride, and wears the middle. So keep that in mind.. Oh yeah, drive a car with tires inflated to the max in rain? That's just asking for loss of traction in either braking or corning, and even hydroplaning. Those numbers are not just random that they post on the door.

As for the max tire pressure listed on the tire? It's just that, it's the max the tire should ever be inflated under any condtions, it's what it's tested to at the rated speed. Go over that or the speed rating and the tire could fail is what they are saying. Just because your engine is rated for 6500 RPM max before redline does not mean you should drive it there all the time. The most I'd go over the door sticker is 5psi, that might gain you some milage but still have a good contact patch. You can also increase it if you have a heavy load in the car. And it usualy is correct, the front will be higher than the rear due to the engine weight, but if so the door sticker will list a higher number for the front than the rears. Toyota has already paid engineers the money to figure out the correct tire pressure for the car, why go around guessing on your own?

There is some tests you can do to find the right pressure for a modified vehical, I do this all the time with modfied trucks with oversized tires for street use, but the point is on a factory Yaris with the factory sized tires it's all been done for you by experts, listen to it.

[Jem_hadar]

Originally Posted by Ziv

No, I don't think there are lots of hills at all. although its call richmond hill, but it's not as bad.

TRUEEEEEEEEEEEe.

I was just there on Monday around 1030am dropping off a friend on my way from TO back to Collingwood.

And yea, RH, not many hills... now fucking NEWMARKET!! THat's a WHOLE bloody OTHER story! Egad! LOL

Newmarkt is BRUTAL for stick IMO!!!

[nwdixieboy]

I got 42.5 MPG in pure highway mileage. I live in Seattle with lots of hills and get anywhere from 25 to 32 in mostly city driving.

[stuffy]

the best i have acheived is 40 mpg on average, and that is driving very easy 50/50 highway/city, tire pressure is checked every 2 weeks

i don't understand how some can get better mileage in the city, driving hard,

are some of us not doing the math properly or can there be that much variation with the same car?

[Ziv]

Originally Posted by Jem_hadar

TRUEEEEEEEEEEEe.

I was just there on Monday around 1030am dropping off a friend on my way from TO back to Collingwood.

And yea, RH, not many hills... now fucking NEWMARKET!! THat's a WHOLE bloody OTHER story! Egad! LOL

Newmarkt is BRUTAL for stick IMO!!!

Newmarket? dude, what da fork are you doing there at the local road? I only drove there during the winter so I felt like I am in a rollercoaster. bahahah, especially on yonge street or bayview. ha ha ha.

[Ziv]

Originally Posted by Tankota

Yes you might get some better milage by increasing your tire pressure above the factory recomended settings - but remember you will also increase uneven wear (the centers will wear out before the edges) your braking will be reduced and your corner grip will be reduced - plus the harshness of the ride will be increased... all cause by overinflating the tires.

The numbers on the door are a result of lots of testing with that size tire on that excact style of car - it's the pressure that gives you the best milage along with the best contact patch of rubber on the ground that size tire for that car. Reduce that, and you get less milage, more wear on the edges, and slop and roll on curves. Increase it, yes you might get some milage, but less rubber and control on the ground, harsh ride, and wears the middle. So keep that in mind.. Oh yeah, drive a car with tires inflated to the max in rain? That's just asking for loss of traction in either braking or corning, and even hydroplaning. Those numbers are not just random that they post on the door.

As for the max tire pressure listed on the tire? It's just that, it's the max the tire should ever be inflated under any condtions, it's what it's tested to at the rated speed. Go over that or the speed rating and the tire could fail is what they are saying. Just because your engine is rated for 6500 RPM max before redline does not mean you should drive it there all the time. The most I'd go over the door sticker is 5psi, that might gain you some milage but still have a good contact patch. You can also increase it if you have a heavy load in the car. And it usualy is correct, the front will be higher than the rear due to the engine weight, but if so the door sticker will list a higher number for the front than the rears. Toyota has already paid engineers the money to figure out the correct tire pressure for the car, why go around guessing on your own?

There is some tests you can do to find the right pressure for a modified vehical, I do this all the time with modfied trucks with oversized tires for street use, but the point is on a factory Yaris with the factory sized tires it's all been done for you by experts, listen to it.

Thank you very much for the detailed info. It's not like I am guessing what would be best for tire pressure to ensure best milage. I just think it would be nice for those of us who share the same car with their own opinion of what they think would be better. Afterall, this is the first car I truly brought myself. I would go anything close to factory made anyways, i think, unless I know more about it, I wouldn't go crazy and pump 10psi over. hehe

[spellcheck]

Thought I'd add this report:
Yaris sedan - automatic
For a 166 mile stretch of highway (I86 through New York State, so quite hilly), I used 3.76 gallons, which is about:

44.1 mpg
(or 5.32L per 100km).

Most of it was at 70mph except for a 20 mile stretch of construction at 50mph. I had the air conditioner on for only a couple of minutes. The trunk was full.

I'm pretty impressed by this little car (assuming I calculated everything correctly, and the trip meter and gas pumps were all functioning properly). I'll have to measure it again on my next trip and see if it compares.