Better mileage after long drive
 

14 base FR-S, just over 1 year now.
16k miles

Just took it on an 600 mile trip, getting 1mpg or better driving to work now. Just put 1/2 a tank of real petrol, no ethanol, in on the trip. Seems to have made a difference as I'm getting 27.5 driving to and fro work now.

Any insights. Cleaner fuel system from all petrol super? Not sure, no other changes otherwise.

How is your MPG being measured?

-alex

Best way to measure it is with gas receipt, pencil and paper. The reading on the odometer is off by a little.

Mine reports increased mileage after highway travel as well in fifth or sixth. It's an extremely optimistic little indicator, off by as much as five mpg sometimes from the actual result from doing the math.

Data is from the car itself via gauges. I do record fill ups via paper log, but didn't check. Just Looking at the car gauge.

I did have that long drive, and put some pure dino fuel in there. That's likely the anomaly. Wondering if injector are that sensitive or of the pure dino petrol cleaned out my system.

It is normal for long drives to increase fuel mileage. Typically on a long drive you stay at a more consistent speed for longer and do less accelerating so your fuel economy is better. It will stay up there for a bit longer when you resume normal driving patterns but will eventually average back out to what you were getting before.

It might be within experimental error ........:popcorn:


humfrz

Unfortunately you can't trust that thing. It is estimating your mileage by average fuel flow rather than actual miles driven divided by actual fuel used. I installed a mileage calculator on my phone (which does the pencil and paper calculation for you at each fill up), and the car's computer is consistently 3 to 4 mpg off.

If you use the car's computer, that bump after highway use could just be a side effect of the way the car calculates fuel economy. If it's averaging fuel flow, and you just had a long period of lower fuel flow, it's going to average that into the initial calculation back in city driving. It would appear to have a bump whether there really is one or not.

Do it with real numbers instead. There's no reason to have to keep a notebook and do math when you can download an app for your phone that will do it all for you.

Nah, assuming the car is in working order with no anomalies the driving cycle, that is the type of driving dictates the fuel economy you get in the moment with no lasting effects.

Highway efficiency > stop and go/city efficiency > wide open throttle

At least, when it comes to your wallet (as pure physics/engineering efficiency favors WOT) combustion engines like steady state.

You're telling us that you're seeing +1 mpg. Is that on your average that you have never reset over 14k miles? Is that on this tank of fuel? Is this on the tank of fuel afterwards? Is this the average of three tanks of fuel?

That statement is open to interpretation so you'll get lots of diagnoses (doctor my stomach hurts, it's either the leftovers or cancer).

By the next tank of fuel you'll be back to normal.

http://www.ft86club.com/forums/showt...18#post2071818

Just reset the Overall MPG reading so you get a more accurate picture for your current trip's MPG. Since it showed the long term average, it's not going to change much in just a trip unless of course you reset it

E85 is a much better solvent that pure gas is.

:thumbsup::thumbsup:

It's always been my understanding that non-ethanol gas will produce better mpg than ethanol "enhanced" fuel. Back in the day when all gas was gas, not a gas ethanol mix, I got 2 to 4 more mpg. Around here non-ethanol is hard to find and usually goes for a premium price. You have to do some number grinding to determine if its worth while.

Yes, ethanol has less energy per unit of volume than 'straight gas' so you will see a mileage decrease as you need to put your foot down a little more to go the same speed. It also corrodes certain rubbers used in older cars and soaks up water which could be bad but typically neither is a problem as most people drive newer cars and we typically burn enough fuel all the time for the moisture collection to ever come to anything meaningful.

Ethanol is more knock resistant so you can run more advanced timing and higher compression ratios to compensate for the lack of energy per volume, that's why E85 tunes show such good gains on stock everything else (Sprint/Outlaw racecars run straight ethanol). And since it is renewable it is likely that ethanol in some form is here to stay to subsidize fossil fuels, it's only cheap now because of government subsidies but the fact that we can grow it and process it on this continent are not something to laugh at.

What I wonder is how is your mileage so low? On my 23 mile commute I would average 30-32mpg with the stock tires. With my new 235/50r17's though.. I think I have lost a bit because of how tall and heavy they are. But I need to do some scientific testing with it as I gave up on tracking my gas mileage after doing it for months lol

on E82 i get 15ish MPG during my normal commute, i can bump it to 17 if i really try. My straight highway mpg on E82-E83, (we hit E85 hardly ever here) is 25-28 depending on the route. one way is a little more up hill. On pump i can get 32-36 highway, and low 30's city.. BUT the extra 115hp make it all worth it

-Thomas

Depends entirely on the commute, stop and go tanks the mileage in this thing, I gave up my long commute and my mileage has nose dived since I'm on city streets instead of smooth flowing freeways (even though they were slow) so my mileage looks terrible but I went from filling up 4x a month to 2x a month roughly speaking.

http://www.fuelly.com/car/scion/fr-s...7974/fuelchart

I used to get high 20's and low 30's really consistently, now I'm low 20's. Although sticky tires and a heavier right foot surely have played a part.

Just used the onboard mileage device. After a tank, it's back to normal at about 26-27 on my commute. Settled back in after a tank of commuting.

Just wondering if it might stick. I know all about that city versus hwy mileage, no need to explain that in detail. But it did stick around for the next tank a bit higher than normal. I'd suspect it had something to do with the all petrol super I put it, couldn't have hurt things, and all petrol does get better mileage than ethanol'd dilutions.

My commute is 80% highway 60 miles each way and I average (odometer/gallons put in) 31-33 mpg going around 75 most of the way. I'm more than thrilled about the mpg, considering I regularly get on it as well.

Nah, it just took a while for your average to come down after the trip. I mix my gas up like some people mix their drinks and use different grades and ethanol or not just about every tank and my average mileage has not budged one single decimal point since I have had the car. I drive exactly the same routes, in the same manner, at the same times every single day so there is no variation in my usage and the different gas has had zero effect.

I do record the data on a mileage log. It's not with me now to review. However, I also reset the mileage estimator each fillup and it's usually pretty close, at least within an mpg typically.

Thanks for the input, I'll have to do the real math from my numbers to find out. I suspect I still had a higher blend of real petrol in there that took 2 more tanks to go through as I filled it up twice when there was only half a tank or so in it because I was heading over the mountain pass with fairly long distances between the next station.

On the way home I topped it off, about 5-6 gallons of typical ethanol blend, then trucked all the way home, 331 miles IIRC, until the thing was on fumes. I pulled into the station and it took 11.46 gallons to fill the tank once I was 2-3 miles from home. That's the furthest I've stretched it on the yellow light, doubt I'll stretch that far again. Car may be considered light at 2750lbs, but that's still a lot to push.;)