fuel est. Miles To Go seems a bit off

[FirstTimerZoomZoom]

First question for my new 2013 MS3.

I went to the gas station after driving 322 miles, and the estimated Miles To Go was showing 11 miles. After filling the tank, it was reading full, but I had purchased only 13.09 gallons of fuel. The owners manual states fuel capacity is 15.9 gallons. How is it that the fuel computer is predicting only 11 miles to go when I have almost 3 extra gallons?

My actual gas mileage after purchasing 13.09 gallons of fuel and covering 322 miles is almost 25 mpg, so the computer should have been telling me I have 75 miles to go, NOT 11.

This is my second tank of gas, and I noticed this the first time, but wanted to record numbers to quantify what is happening.

Wondering if anyone else has noticed this?

[nekret]

Same thing here on a 2011 MS3... Its a pretty common practice for manufacturers to pretend 10-20% of the bottom of the fuel tank doesn't exist. I think the most likely reasoning on this is ensuring there is a very large safety margin between 1 mile of range left and true empty thus reducing any pissed customers that say the range still had 1 mile on it and the gas station was only 9/10 of a mile away :-)

Another possibility that I'd suspect is its to prevent premature low pressure fuel pump failure. Gas acts as both a coolant and a lubricant to in-tank fuel pumps so if the tank is taken all the way to empty they tend to burn out faster. This is my experience with dealing with college kids' cars vs. their parents who fill up at 1/4 tank every time.

Generally speaking I just fill up when the low fuel light comes on, takes 12-ish gallons so I know there is still plenty of fuel around the pump and the range meter typically reads about 30-50 miles remaining.

[FirstTimerZoomZoom]

Originally Posted by nekret Same thing here on a 2011 MS3... Its a pretty common practice for manufacturers to pretend 10-20% of the bottom of the fuel tank doesn't exist. I think the most likely reasoning on this is ensuring there is a very large safety margin between 1 mile of range left and true empty thus reducing any pissed customers that say the range still had 1 mile on it and the gas station was only 9/10 of a mile away :-) Another possibility that I'd suspect is its to prevent premature low pressure fuel pump failure. Gas acts as both a coolant and a lubricant to in-tank fuel pumps so if the tank is taken all the way to empty they tend to burn out faster. This is my experience with dealing with college kids' cars vs. their parents who fill up at 1/4 tank every time. Generally speaking I just fill up when the low fuel light comes on, takes 12-ish gallons so I know there is still plenty of fuel around the pump and the range meter typically reads about 30-50 miles remaining.

This makes perfect sense. A good safety precaution to underestimate the remaining range.

As a side note, I am surprised my gas mileage is better than published. I am getting nearly published highway mileage in mostly city driving and some highway driving. Then again, I am still in the break-in period, so this might get worse over time

[abelardo]

OP, what are you doing to get that kind of mileage? I barely break 220 per tank mostly city driving.

[Pu Manchu]

they underestimate the range so you don't buttfuck your in tank fuel pump trying to suck gas out of the bottom of the tank.

congrats on your first car.

[FightaX]

Originally Posted by FirstTimerZoomZoom First question for my new 2013 MS3. I went to the gas station after driving 322 miles, and the estimated Miles To Go was showing 11 miles. After filling the tank, it was reading full, but I had purchased only 13.09 gallons of fuel. The owners manual states fuel capacity is 15.9 gallons. How is it that the fuel computer is predicting only 11 miles to go when I have almost 3 extra gallons? My actual gas mileage after purchasing 13.09 gallons of fuel and covering 322 miles is almost 25 mpg, so the computer should have been telling me I have 75 miles to go, NOT 11. This is my second tank of gas, and I noticed this the first time, but wanted to record numbers to quantify what is happening. Wondering if anyone else has noticed this?

Basically, when your car hits 0 miles on the "RANGE MILES" on the screen, you have about 1.5-2 gallons of reserve fuel. Yes, the gas tank has 15.9 gallons ~ 16 gallons. So if you filled up gas @322 miles w/11 left over on the "Range Miles" on the screen, and you roughly had approximately 3 gallons left in the tank. So you could have gone 322 + 11 + 75 = 408 total miles, but you'd probably run out of gas at that point. Doing the math here, it would avg @ ~ 25.5 MPG.

I was bored sorry.

[LumberJack]

Originally Posted by abelardo OP, what are you doing to get that kind of mileage? I barely break 220 per tank mostly city driving.

That really sucks, sounds like you need to take a look at your driving style... I'm BT beat the living crap out of my car daily, 85% city driving and I go further than that on a 40% E85 mix... Highway driving on E85 I go over 300....

[FirstTimerZoomZoom]

Originally Posted by abelardo OP, what are you doing to get that kind of mileage? I barely break 220 per tank mostly city driving.

The following is true for all cars, some will be easier to do that others, firstly, make sure your tire pressures are correct as published on the drivers side door jam. Do not wait for the "low tire pressure" indication to come on. This needs to checked once a month.

Use the right gas for your car, minimum 91 octane. I've known some to use lesser octane ratings for other cars requiring premium, but this reduces gas mileage. I have heard some mods might improve gas mileage at the same time increasing HP and torque. Maybe someone can confirm this.

Now the hard part. What makes this car fun to drive is that the gearing is perfect for the city, with max torque in the usable range. But this is also what produces the worst gas mileage. You need to come up to speed slowly, and keep the tach below 3,000 before shifting. Also don't go faster than 65 on the highway, higher RPMs means less gas mileage.

The way I see it, keep your "fun" driving for special moments, like scaring your GF or wife, or putting a smile on the kids face, this will also lower the chances of getting too many tickets.

Originally Posted by Back Titties congrats on your first car.

This is my first Mazdaspeed, I've had many other cars, but nothing like this one

[Alexander]

just ignore it. I've driven 40 miles with the range saying 0 before, when I filled up i got 15.2 gallons of gas (lol close). basically when it gets to 0 is when you should think about filling up

[abelardo]

Originally Posted by FirstTimerZoomZoom The following is true for all cars, some will be easier to do that others, firstly, make sure your tire pressures are correct as published on the drivers side door jam. Do not wait for the "low tire pressure" indication to come on. This needs to checked once a month. Use the right gas for your car, minimum 91 octane. I've known some to use lesser octane ratings for other cars requiring premium, but this reduces gas mileage. I have heard some mods might improve gas mileage at the same time increasing HP and torque. Maybe someone can confirm this. Now the hard part. What makes this car fun to drive is that the gearing is perfect for the city, with max torque in the usable range. But this is also what produces the worst gas mileage. You need to come up to speed slowly, and keep the tach below 3,000 before shifting. Also don't go faster than 65 on the highway, higher RPMs means less gas mileage. The way I see it, keep your "fun" driving for special moments, like scaring your GF or wife, or putting a smile on the kids face, this will also lower the chances of getting too many tickets. This is my first Mazdaspeed, I've had many other cars, but nothing like this one

It's hard to keep it under 3000K, I'm pretty sure it's the main reason why my gas milage is so low. Congrats on picking up your mazdaspeed and enjoy the boost bro!

[El Beaner]

Still trying to decide which app is best, but these are my results.

This is mixed city/hwy driving mostly. I'd say roughly 50/50 of each

Acar


Fuel Log

[Ziggylittles]

Originally Posted by abelardo It's hard to keep it under 3000K, I'm pretty sure it's the main reason why my gas milage is so low. Congrats on picking up your mazdaspeed and enjoy the boost bro!

If your car is revving to 3000k I think you have a problem my friend.


Tap

[abelardo]

Originally Posted by Ziggylittles If your car is revving to 3000k I think you have a problem my friend. Tap

You haven't heard about the Galaxy Galactical head, cam and valve upgrade? Starship enterprise style.

[JgamB]

The pessimistic fuel gauge is a bit unnerving if you're filling up with E85 for your first mix. You plan on putting in 3/9, and oh shit... you can't get 12 gallons in the tank from what looked like damn near empty. Yeah, it definitely leaves some room for error (and pucker factor).

I just ran mine down to 2 bars today to flash back to my 93 tune. I have some highway miles planned for this weekend, and I was due for a clean up tank. The highway mileage when tuned is pretty damn amazing, with 32 mpg being very attainable.

[mg446]

I''m about 320 miles/tank depending on how much I run WOT on 93 octane.

Originally Posted by Ziggylittles If your car is revving to 3000k I think you have a problem my friend. Tap

I can easily keep mine under 2.5k rpm? why 3k rpm ?

[Vansquish]

Originally Posted by nekret Same thing here on a 2011 MS3... Its a pretty common practice for manufacturers to pretend 10-20% of the bottom of the fuel tank doesn't exist. I think the most likely reasoning on this is ensuring there is a very large safety margin between 1 mile of range left and true empty thus reducing any pissed customers that say the range still had 1 mile on it and the gas station was only 9/10 of a mile away :-) Another possibility that I'd suspect is its to prevent premature low pressure fuel pump failure. Gas acts as both a coolant and a lubricant to in-tank fuel pumps so if the tank is taken all the way to empty they tend to burn out faster. This is my experience with dealing with college kids' cars vs. their parents who fill up at 1/4 tank every time. Generally speaking I just fill up when the low fuel light comes on, takes 12-ish gallons so I know there is still plenty of fuel around the pump and the range meter typically reads about 30-50 miles remaining.

This isn't strictly accurate. The fuel light is supposed to illuminate with ~50 miles worth of gas remaining to prevent people from A) running out of gas, and B) destroying the in-tank fuel pump by running it dry. This gives you the buffer you're suggesting.

What you have to understand about the estimated fuel miles to go calculation is that it's based on a variety of factors, not simply the actual amount of gas remaining in the tank. It essentially forecasts your mileage based on how far you'd traveled at the same point on the gas gauge on your last tank and interpolates based on how you're driving on the current one. If that doesn't make sense, consider the following (real) example.

I drove a 2011 MS3 for an entire tank of gas on the highway, babied it, and got pretty close to 35mpg overall. Estimating the full range for 15.9 gallons, that's around 550miles (though I didn't empty the tank completely). The next tank was mostly city driving, and I averaged about 22mpg for an estimated full range of about 350 miles (again, I didn't completely empty the tank).

During the first tank, the "estimated distance to empty" reading initially told me that I'd only manage around 400miles for the tank, but of course, by the end I'd gone something like 515 miles.

During the second tank, the "estimated distance to empty" reading initially estimated something in the low 500 mile range (maybe 503 . . .can't remember), but I only managed to go about 307 miles before the gas light came on.

Basically, what I'm telling you is that that gauge isn't worth fuck-all. It's all about how you drive the car.

Originally Posted by abelardo OP, what are you doing to get that kind of mileage? I barely break 220 per tank mostly city driving.

What are you doing to only get 220miles in the city? You should be able to do better than that. That's only 13.8mpg! It sounds like, as a few others have already said, you need to change your driving style. Keep in mind, it's not all about the low revs. It's about low revs AND low load conditions. The moment you start commanding enough load to switch into OL, you're going to start running unnecessarily rich and your fuel economy will fall like a stone.

Originally Posted by Back Titties they underestimate the range so you don't buttfuck your in tank fuel pump trying to suck gas out of the bottom of the tank. congrats on your first car.

This is part of the answer, but not the whole answer. See above.

Originally Posted by mg446 I''m about 320 miles/tank depending on how much I run WOT on 93 octane. I can easily keep mine under 2.5k rpm? why 3000k rpm ?

2.5k = 2500rpm
3000k = 3000000rpm

[abelardo]

Originally Posted by Vansquish What are you doing to only get 220miles in the city? You should be able to do better than that. That's only 13.8mpg! It sounds like, as a few others have already said, you need to change your driving style. Keep in mind, it's not all about the low revs. It's about low revs AND low load conditions. The moment you start commanding enough load to switch into OL, you're going to start running unnecessarily rich and your fuel economy will fall like a stone.

I only drive it once maybe twice a week unless I autocross it. 220 was to just under a quarter tank and I was running 3" sri/tip w/o the calibration.

Now that i'm calibrated correctly I should see higher mileage.

[mr.speedy3]

Originally Posted by LumberJack That really sucks, sounds like you need to take a look at your driving style... I'm BT beat the living crap out of my car daily, 85% city driving and I go further than that on a 40% E85 mix... Highway driving on E85 I go over 300....

How in the hell do you do over 300 on E85? I am on the baby k, with 3 gallons of E to a full tank and can pull 300 on a good week.. And I drive 60miles a day on the freeway. To be fair, that's at 74mph usually.. I'm sure if I drove at lower speeds I could get better gas mileage... Suppose I should factor in my sporadic driving when I am bored lol. So maybe... your statement still stands... Lately though, I weened off E (being lazy since E isn't close to me anymore) since I has meth now. My MPG is definitely way the hell up there compared to what it was with E lol.

[Pu Manchu]

@mr.speedy3; fuel is added based on air, and your right foot controls how much air goes into the engine..

[mr.speedy3]

Originally Posted by Back Titties @mr.speedy3; fuel is added based on air, and your right foot controls how much air goes into the engine..

The spark coefficient of E85 is less than that of 91...

[Pu Manchu]

Originally Posted by mr.speedy3 The spark coefficient of E85 is less than that of 91...

you sound like a cunt. try driving a whole tank without passing 2500rpm and see if my theory is correct. please report back.

[mr.speedy3]

Originally Posted by Back Titties you sound like a cunt. try driving a whole tank without passing 2500rpm and see if my theory is correct. please report back.

Since when does being knowledgeable make someone a cunt? Fuck yourself.

1 gallon of E85 has 73% to 83% of the energy of one gallon gasoline (variation due to ethanol content in E85). Ethanol's energy content can range around 76,000 Btu/Gallon - 85,000 Btu/Gallon. Gas is ~116,000 Btu/gallon.

So tell me how running gas that is 83% less efficient at its best, is the same as 100% efficient?

[Pu Manchu]

now you look more like a dumb cunt instead of just a cunt.

so on a given fuel, are you saying you will get more or less fuel economy by opening the throttle less?

i await bestowal of your knowledge.

[Vansquish]

Originally Posted by mr.speedy3 Since when does being knowledgeable make someone a cunt? Fuck yourself. 1 gallon of E85 has 73% to 83% of the energy of one gallon gasoline (variation due to ethanol content in E85). Ethanol's energy content can range around 76,000 Btu/Gallon - 85,000 Btu/Gallon. Gas is ~116,000 Btu/gallon. So tell me how running gas that is 83% less efficient at its best, is the same as 100% efficient?

Originally Posted by Back Titties now you look more like a dumb cunt instead of just a cunt. so on a given fuel, are you saying you will get more or less fuel economy by opening the throttle less? i await bestowal of your knowledge.

Now now children, you're going to confuse the n00bs.

1. Opening the throttle less will help you get better fuel economy regardless of the frame of reference (which fuel you happen to use).

2. Keeping the engine in low-load conditions will also help you get better fuel economy (basically downshift to the right gear to keep calc. load below 0.8 if you want to get decent fuel economy).

3. E85 is a less energy-dense fuel than 93 octane pump gas. As a result, no matter how well you're tuned for it, you will be able to travel less distance on a full tank of E85 or E50, or e22, etc. than you would be able to travel with a full tank of 93 under otherwise identical conditions.

[chaser27]

Somebody had to say it... E85 doesn't have as much energy in it as 93. You can only fit the 15.9 gallons or whatever it actually is. More energy = more miles