MPG with different fuels

With just 1150 miles so far, I'm curious about how you adequately separated fuel differences from the many other confounding differences.

 

I was wondering too about that. Been driving in Eco mode since I picked up my car from the Dealer. It was their recommendation for best fuel economy. Now decided that if you're a careful driver with your acceleration - you don't need it. You can achieve the same fuel efficiency on normal mode. (plus I'll avoid annoying drivers' behind me with the slow starts). In Australia - our Prius C Handbook recommends that for optimum engine performance, unleaded gasoline with a Research Octane Number of 91 or higher should be used. Couldn't tell you about the mpg yet as i haven't gone for my 1st tank fill. only had my c1 for 2 weeks. I can say that it's done 324km & the performance feels "great". so far i've lost 3 bars off the fuel guage from a full tank?. that's pretty impressive. This car is phenomenal!

 

The OP's reply illustrates that he didn't. The OP was mixing gas from various sources and not doing controlled tests.

Bwilson4web did some gasoline tests and in order to flush out any old fuel, he intentionally he ran his cars out of gas, many times. I have some links to some of his posts at Need input for gas mileage experiment. Please Help!! | PriusChat but unfortunately, due to the Priuschat switchover, the links point to the right thread, but not the right posts anymore.

Does Octane affect mileage? | PriusChat were some of Bob's results.

Re: "negative feedback", well, the OP needs to recognize the above and have proper experimental design and procedures. Without them, the results and conclusions drawn may not be correct.

 

I wanted to try a non-ethanol gas, but the only station that advertises it had mid-grade at $3.96 gallon. I paid $3.07 gallon at my normal station for 10% ethanol blend. The difference in price didn't justify the extra mpg's I thing I would get. I still get consistent 52-54 in '10 Prius IV.

 

What negative feedback? If you saw it in mine, then you completely misread it. And wait more than an hour before assuming no answer, as few readers are plugged in here fulltime.

These partial refills still leave a lot of old fuel in the tank mixture, making it impossible to have measured real mpgs for both ethanol and no-ethanol over this short distance. Combined with variations in roads, traffic, weather, and likely rapidly improving driving skill in this new car, it is very unlikely that the mpg change observed in the base post was a meaningful characterization of fuel differences.

Several drivers (see links in Cwerdna's post) have done other fuel comparisons. Give them a read, then give this another try.

 

People often are confused about what eco mode does. Mostly, it adjusts the response curve of the accelerator. This means any acceleration can be achieved in either eco mode, normal mode, or power mode. The difference is that normal mode is (roughly) linear, eco mode has more sensitivity in the lower range, and power has more sensitivity in the higher range. I (and many others) find that sensitivity in the lower range is more helpful in driving efficiently than sensitivity in the higher range. But with a talented enough ankle, you can drive exactly the same in any mode (and get roughly the same MPG).

Mode doesn't make any difference in how fast you start (other than the above, i.e. how fast you can move your foot), and with almost 300 ft-lbs of torque at 0 RPMs you should beat most everything in the first few seconds.

 

I think that there is less performance difference between regular and premium fuel than there is with the alcohol content of the fuel.

To the OP, don't get turned off if you don't always get courteous answers to your questions. This is a great site and we love having good members like you.

 

There is little to no difference in energy content between regular and premium. If you engine isn't knocking, there is no reason to pay extra for premium (or plus).

E10 has 3.3% less energy content than straight gasoline. If the price of straight gas is more than 3.3% more than E10, it isn't worth it.

 

If you believe that was critical, then I don't know how to prepare you for the working world.

As another member replied, your second post reinforced the feeling that the fuels were not adequately separated. I have already run a preliminary spreadsheet to estimate how much of a mixing problem between new and previous fuels was likely present. If you can correct and add more detail to the fuel log below, particularly by listing which kind of fuel was used for each fillup, then I can refine that sheet and we can discuss what was good the first time and what should be improved on the next tests:

Fillup# gallons_added Fuel_type Odometer MPG
Delivery >10.5 unknown tbd na
#-1 2.xx tbd tbd tbd
#-2 7.00 tbd tbd tbd
#-3 6.00 tbd tbd tbd
#-4 5.00 tbd tbd tbd
#-5 3.07 tbd tbd tbd
#-6 5.00 tbd tbd tbd

(sorry about the missing formatting, there is still much to be learned about the new website system)

 

Thanks for that. You could be right? - although, I'm still experimenting with it...& it's not going to be my ultimate conclusion?. I'm merely expressing "my" experience so far on how the car performs, purely by feel. To me,, Eco mode is like a heavy pedal,,,where u gotta push it hard to the floor to get it going, whilst avoiding the redline on the eco score graph. It's a SLOW "glide" acceleration that feels like forever to get from 0-40km? I've had "A-hole" drivers go right up my bumper because of it. God it's intimidating i must say! I wonder if they do it on purpose because they know it's a Prius?? - anyhow.....I found Normal mode is a quick starter. Lighter pedal...no hassles staying in the graph.'easy' ....0-30km in 3 SECONDS which is quick off the line! and (no harrassment from other impatient drivers. ) Also noticed the engine switching to EV more often than in Eco mode? I think it's a personal choice what you try to achieve with your car, & being comfortable with it.
By the way - this car is a huge step down for me. My past cars have been v8's. the most powerful being a chevy 350 worked motor with sports cam etc etc. So I've grown up in fast cars. Also been in the drag racing scene. - and now OVER IT.
But i gotta say....I've never had drivers kissing my back bumper,, because they wanna run me down?!
I kinda feel offended by it - because here in Australia - they hate Hybrids & don't believe in them! They're considered as slowwww 'electric' false cars.
Although the 2nd gen Prius's are out in numbers here as family cars & Taxis...... they've BEEN noticed. ...but still loathed. Haters will be Haters???.
Nevertheless - i turn a blind eye to it - and drive my Prius C proudly.
I've only spotted 1 c in my town .... Plus Mine. Not many people know about them? . I wonder how long it'll take before I spot more C's in Adelaide?

 

I don't think fuzzy1's response was all that out of line. 10 days is hardly a long enough time to adequately determine much of anything other than cup holder sufficiency. And sometimes it takes a day or two to get very many responses, and waiting half an hour is just not gonna cut it. Being a new and excited PC member only goes so far.

I've had mine two months and 3500 miles. I have determined there is little enough difference between regular and premium with this car to see any difference in mpgs. My last five tanks have been in the 51.x mpg range, and more than one of those was premium or a high premium percentage.

I had determined in years past that ethanol was not worth the time or trouble with it's decreased mpgs and more corrosive nature.

Better to pump up the tires and drive like the car wants. You'll only learn what the car likes with time and miles.

I managed a 2 mpg increase in best-mpg drive to work using ECO mode this morning. 68 vs 66 from the scangauge. 12 miles. I think ECO mode also makes it go into EV mode sooner/longer.

 

Franathan, Greetings!

There are tailgating morons everywhere. In the states I think there are pockets of haters everywhere, interspersed amongst super-busy and the super self-important and impatient types.

In my experience they are all in a hurry and will go around at the first opportunity. Where I live there are few single lane roads, giving loads of opportunities to go around me if required. Sometimes accelerating a little slower will help them move around you and go on to tailgate the next guy in their way. Slowing down ever so slightly will assist even more.

I have yet to feel endangered by a frothing at the mouth type. But I suppose it's only a matter of time. I have a rather large and hard flashlight to help that person "see my side" if it comes to that, but with my luck they'll have something better.

 

Sadly, it is what is most widely available. I have to go far out of my way (to a single station) and pay a hefty premium for what I presume is higher octane gas (and ethanol-free).

I'll be seeing if it was worth the trouble mpg-wise in my case.

 

LOL! thanks & Greetings to you too Mr Incredible, - Been tempted to yell out to those morons through my window as they drive past & throw a bit of sign language (if u know what i mean?) - But it's not lady like lol . i think your helpful tips are far safer & better -Anyway, According to a survey - Adelaide's been labelled the worst state in Australia, for Road Rage. . I'm definitely NOT one of those drivers' - but i do believe it. Got a main street that runs past my front house,,,& the loud, vulgar abuse i've heard amongst impatient drivers' during peak traffic- it sounds like they're ready to jump out their car & kill??!!............... sheezz ? ..........why don't people just chill??? it ain't the end of the world?

 

^Looked around lately? It may be.

 

I used to be the road rage type. I'm trying hard to be more mellow in my old age and let the world flow around me rather than barging through it. Getting my CRX helped. Getting the Prius helped. Driving my 10mpg truck REALLY helped when the gas prices started to skyrocket and I drove a lot more slowly.

Everything is temporary. Nothing is permanent. In 10-20 seconds it's all over, the idiot driver has passed, and sun comes back out from behind the clouds.

Ommmmmmmmmmmmmmmmmmmmmmmmm. (repeat as required.)

 

I do not think you will see any increase with a higher octane.

What you will see (as many others are seeing, including myself) is an increase
using pure gas.
I started two tankfulls ago, and you get over 10% more gas (it wont give you 10% more mpg though)
I have increased mpg from 52.7 to 53.5 and last tank was 56.4

I see an increase of about 7%
yes, many factors excluded there, but that is what I see and I am loving it.

remember 100% pure gas!