Fuel Economy

[punch]

Originally Posted by 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.

wow thats almost better then the listed epa ratings...

[NickNickNick]

Originally Posted by Ziv

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

My tires are all set to 32psi (checked at least weekly) and I have been getting 43mpg in city average and 54 highway.

[stuffy]

nicknicknick, are you sure you are calculating properly? i can't see this car getting anywhere near 54 mpg, that is what many report the prius hybrid as getting

[Ziv]

You guys got some ridiculus numbers. When is it going to be MY TURN!

[punch]

Originally Posted by Ziv

You guys got some ridiculus numbers. When is it going to be MY TURN!

well in my case it was the first tank, I drove slow, never going above 130km/hr

on my current/secound tank, i'm just driving normal without looking at the gas uasage, and i can see its burning it faster, but i also have driven at 140 too...

will post the results of my secound tank when it runs empty..

[NickNickNick]

My last highway trip I drove 710kms on 38-39 litres.

My last city fill was 31L on 478kms.

I will say that I live in Saskatchewan, and there are virtually NO hills at all, though the highways are crappy enough that there is a lot of slowing and accelerating on the highway.

[why?]

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.

Toyota engineers are recommending settings for 1 thing only - safety. They have to assume everyone that drives the car shouldn't really have a license, so they have to make all settings super-conservative so that the morons don't kill themselves and Toyota doesn't get sued.

No one ever recommended over-inflating tires.

Tire manufacturers know more about their tires than Toyota does. They know what is safe, and what the tires will handle.

Using the maximum pressure of a tire will not cause uneven tire wear as the manufacturers have created the tires to run at that setting.

It is always best to trust the manufacturers of a component over the manufacturer of the entire car.

[Idjiit]

Originally Posted by why?

Using the maximum pressure of a tire will not cause uneven tire wear as the manufacturers have created the tires to run at that setting.

It is always best to trust the manufacturers of a component over the manufacturer of the entire car.

This really isn't true. Tires don't exist purely outside the context of the car they're attached to. The performance characteristics of the same tire attached to a 2,000lb car vs. a 4,000 lb car are going to be different. You cannot simply say "the max tire pressure is 44lbs, so that's what I'm going to use". It just doesn't work like that.

[foober]

another thing to take into account. Is the gas stations you fill at. I just filled half my tank and found I am now only getting 36 miles to the gallon. My last three half fillups came out to 40 miles to the gallon at another gas station. Then I went to this other gas station and wound up after the calculations of getting the 36 miles to the gallon. Could it be that gas station meters out gas differently.

[Idjiit]

Originally Posted by foober

another thing to take into account. Is the gas stations you fill at. I just filled half my tank and found I am now only getting 36 miles to the gallon. My last three half fillups came out to 40 miles to the gallon at another gas station. Then I went to this other gas station and wound up after the calculations of getting the 36 miles to the gallon. Could it be that gas station meters out gas differently.

Yes, this is the fundamental flaw in the self-calculation method. Depending on the pump, how far you have it stuck in, etc. the amount of gas dispensed on a fill up can vary.

[swng]

Seems you have a reason to suspect foober. On the other hand, the meters are checked regularly, if I remember what I have read from elsewhere correctly. Too many factors influence our calulation results and that is why I suggest to record our numbers for the long term so that a more reliable average can be worked out.
I have not done well with my latest tank either. It yielded only about 37.3 mpg(imp) or roughly 31 mpg(US). That must have been one of my not-so-good tanks. There have been many short trips in the city and the A/C was on for a number of times.
Thanks for sharing your numbers.

[swng]

Originally Posted by Idjiit

Yes, this is the fundamental flaw in the self-calculation method. Depending on the pump, how far you have it stuck in, etc. the amount of gas dispensed on a fill up can vary.

Valid observation! Thanks! Hopefully long term average numbers can somehow compensate for the errors resulting from the variations that we cannot control each time we do the calculation after a fill-up.

[why?]

Pumps must dispense the correct amount. They are all checked.

However different brands of gas can give different results. That is why it is good to find a gas that gives results you like and stick with it.

My first 2 fill ups, finally:

1st to make sure the tank was fill from the dealership: 19 miles, .688 gallons = 27.62 mpg.

2nd one today, 460.2 miles, 10.85 gallons = 42.41 mpg.

Total so far = 41.53 MPG.

That equals 5.66 l\100 km or 49.88 mpg Imp.

[swng]

Originally Posted by Ziv

My, my. I wil keep that in mind! Thanks!

Hi Ziv, on this page, you will find some information about what we have been talking about i.e. the higher is the speed above the car's optimal speed, the higher is the fuel consumption rate:

www.fueleconomy.gov/feg/driveHabits.shtml

Hope you like it.

Edit: After reading the Driving More Efficiently page, please also go to the Gas Mileage Tips page (click on the left near the top of the Driving More Efficiently page) and watch the MotorWeek video. It is very relevant and very good! Enjoy!

[Idjiit]

Originally Posted by why?

Pumps must dispense the correct amount. They are all checked.

I didn't say that pumps won't dispense the "correct" amount. I'm saying that the sensors in the pumps in conjunction with how you use it (and environmental conditions) will vary how much is able to be dispensed. The self-calculation method hinges on the idea that you're getting a "full" fill-up every time. These variances can lead to miscalculations.

[stuffy]

yeah, you have to average over a number of tanks to get an accurate idea of your fuel consumption, this will factor in the varying driving styles and conditions as well.

[Ziv]

Originally Posted by swng

Hi Ziv, on this page, you will find some information about what we have been talking about i.e. the higher is the speed above the car's optimal speed, the higher is the fuel consumption rate:

www.fueleconomy.gov/feg/driveHabits.shtml

Hope you like it.

Edit: After reading the Driving More Efficiently page, please also go to the Gas Mileage Tips page (click on the left near the top of the Driving More Efficiently page) and watch the MotorWeek video. It is very relevant and very good! Enjoy!

Sweet, man. I will check it out! looks like its gonna help. Maybe I do have a bad driving habits. bahahaha.

Another update:
460 km/ 32 Litre
6.96 l/100km. Sweet justice, juicy sweet justice. I have finally get under 7 for ONCE! This could be a dream, don't wake me yet if this indeed is a dream.

[swng]

No, it is not a dream. With a Yaris, reasonably good fuel economy like that you have just posted is actually achievable and you have proved it. I feel so happy for you!
Cheers!