100 MPG per Quarter Tank,

[djpatm]

Due to trying to take advantage in crazy changes in gas price I haven't really been able to run out more then half a tank so I'm not sure what the full MPG is but on average I seem to be burning a quarter tank every 100 miles in my Speed 6 with 31000 miles on it. Completly stock.

Is that normal? I've heard mixed reports from friends simply cause were all used to kilometers here and no is really sure and were never in the mood to actually do the conversion and all that lol.

Also I heard the gauge is very off aswell so is there any other way to tell?

[obsoletee]

I do the same on my first quarter tank with my non speed 6s. My guess is the first quarter tank is a bit larger than the rest of the tank.

[BoostedSpd6]

the gauge in the speed 6 is off to some degree but i got and outstanding 34.7 mpg on my trip to florida and back with my speed 6 ..others have gotten good gas millage in the 30 plus range on long trips as well theres a thread about it somewhere. the 100 miles every quarter tank by the gauge seems good thats 400 miles on a full tank. but i was getting 380 to 365 on 10 gallons and the gauge would be close to the line next to E. so the gauge seems to be off in that reguard.

[obsoletee]

I am taking a trip to Toronto tomorrow, finally going to test a tank with nothing but highway, I will post numbers when I return.

[obsoletee]

Also I have an 18 gallon tank and the low fuel light comes on when I have 3-4 gallons left. I don't have the balls to run it down anymore.

[Igve2shtz]

The gas gauge is very inaccurate in the MS6, or atleast mine.

For example, when you go to fill the tank, the needle goes above the F mark, so this is already not a good way to gauge efficiency.

For mine, it takes 125 miles for it to go from F to the 3/4 mark. Then 100 miles later, it goes to 1/2, and another 75 miles later, it goes to 1/4, and i swear, it takes less than 50 miles to go to E.

I average about 24-25 mpg on any given week. On road trips, it extends out to 30-32. Its awesome.

Your best bet for determining fuel efficiency is to go to a gas station, and when the nozzle first shuts off, just pay. Do not top it off. Then, reset the tripometer, and drive around for a week, and try to go to the same gas station, the same pump, and fill up again. Take the amount of miles you have driven, and divide by the amount of gallons it took. This seems to be the best way to produce consistent enough numbers.

[chuyler1]

I've never gotten more than 28mpg in my MS6 (calculated after a single full tank). I always fill up to the top and run to 20-40 miles past the warning light and I usually get between 360-400 miles per tank.

I'm always curious as to whether those claiming better mileage are running on smaller tires...because even the same tire size can differ enough to throw your calculations off.

[sykopat]

Wow, 360-400miles per tank??

I'm currently averaging 360-400kms per tank!!! That's like 225-250miles per tank... and I'm completely stock!!!

I'm using 94 octane fuel in case anyone would wonder.

[chuyler1]

I have never, even after spirited driving, had to fill up before I passed the 300mi mark (I use 93 octane and the drivetrain is completely stock btw). So if you're only getting 225-250mi then either you drive like a bat out of hell or there is something wrong with your car.

What size/brand/model tire do you have?

[sykopat]

I must admit that I've been in traffic, mornings and evenings, for the past month. But even before that, I rarely reached the 400km/tank (250miles).

I currently have 3000km old Falken FK-452 on stock wheels, in size 225/40R18.

I bought the car used, at 54 500km and I'm currently at 58 300km, so it's really hard to tell for me if the car feels like it should.

[chuyler1]

The 225/40R18 tires are in theory 2% smaller than the stock 215/45R18 meaning your mileage reported by the speedo should be 2% farther than you actually traveled...which should work in your favor I would think.

Getting stuck in stop-and-go traffic something I don't have to deal with. I have a few traffic lights I need to get through but out of my 30 minute commute I am probably stopped for at most 5-10 minutes, the rest of the time I'm cruising at 35-45mph.

If your tail pipes are getting covered in soot you may want to think about having the dealership re-flash the ECU to make sure you have the most recent map. Other than that all you can do is check tire pressure and make sure the wheels are aligned and not wearing the tires unevenly.

[Igve2shtz]

I am running stock wheels/tires. Right now, I only have an ETS TMIC and test pipe in, and I pull the same numbers as I did stock. I've noticed that inorder to break 28 mpg I have to use cruise control like 3/4 of the time. And, the times I broke the 30 mpg barrier, I also drove like 300 miles without turning off the engine, so there was no warm up period where the cars run mad rich.

[BADFISH6]

Im not even getting close to this kind of gas mileage and im basically stock. I get 18, 19 mpg max (sometimes 20 if only highway). What do you guys shift at?

[obsoletee]

Just got back from Toronto and was only able to muster 27mpg on my 04 Mazda 6S. I used cruise most of the time and never once hit WOT. I really was expecting a bit better.

[chuyler1]

I shift between 3-4K unless I've got open road and 50+ mph speed limits.

[djpatm]

Well I'm at roughly 250 miles, 2 1/2 quarters into my tank... This is apparently where the needle plummets so we'll see...

Hopefully I can get through the weekend... 9-10 days of gas... It makes me cry. 1.21 a litre here too. Fuckin' Hawaii has cheaper gas then we do and there on a fuckin' island in the middle of nowwhere and we're a few hours away from the gigantic fort mcmurray oil sands...

[sykopat]

I shift between 3-4K unless I've got open road and 50+ mph speed limits.

That's usually where I shift at too. Thanks for the tips, by the way. (2thumbs)

[sykopat]

Well I'm at roughly 250 miles, 2 1/2 quarters into my tank... This is apparently where the needle plummets so we'll see...

Hopefully I can get through the weekend... 9-10 days of gas... It makes me cry. 1.21 a litre here too. Fuckin' Hawaii has cheaper gas then we do and there on a fuckin' island in the middle of nowwhere and we're a few hours away from the gigantic fort mcmurray oil sands...

1.21$/L and it makes you cry? :D
Try 1.59$/L for the 94 octane! (argh)

[djpatm]

Oh it's roughly the same here for 94.
Thats just the regular price. I put premium in (mostly 91, only know of one place that offers 94 and there gas is pretty sketchy) but I'm not sure what it's sitting at.

I hate gas.

[Wagonbacker9]

somewhat off topic:
nearly all gas gauges read slowly when the gauge is close to full, and quicker when you get toward the bottom. this is because typically there is a float at the end of a rod on a hinge. (as opposed to some sort of slide mechanism that would be more accurate, more expensive, and more prone to failure) the gauge reads based on where the rod is pointed, and if you think about it... as the float drops lower, the hinge will have to move farther near the bottom of a circle than at the top.

visualize it this way: hold your arm strait out in front of you. in order to move it down one inch, you only have to move an inch. now hold it at a 45 degree angle down in front of you. in order to move it down one inch (change in fuel level) you'd have to move it about 2", because to move DOWN one inch, you also have to move it back an inch. The ratio would get worse as you get further and further down.

[BADFISH6]

I shift between 2.5k-3k and recorded 123 miles for a half tank. I think thats about 16 mpg and as i said i get max 18mpg. I usually drive very short distances, not normally longer than 7 or 8 miles. Could this account for my terrible gas mileage?

[djpatm]

Well quarter tank left and I'm at 281 miles. Dammit I AM making it too 300 lol

[Wagonbacker9]

I shift between 2.5k-3k and recorded 123 miles for a half tank. I think thats about 16 mpg and as i said i get max 18mpg. I usually drive very short distances, not normally longer than 7 or 8 miles. Could this account for my terrible gas mileage?

definitely. if you're driving that short of a distance, your car isn't reaching its optimal operating temp and thus isn't running efficiently, plus if its that short I'd bet its a lot of stop and go too.

[djpatm]

So I think I figured it out... I filled up I'd say a quarter of a quarter or half of a quarter away from the Empty line. I got 311.2 MILES on the tank and put in 50.99 LITRES (I imported my car from the states) and that was till the second auto-off, click thing. Exactly like the time I filled up before when I started counting. So my calculations should be pretty close to perfect.

Anyway, 50.985 litres equals 13.47 Gallons so my MPG =

23.1 or 10.18 L/100km

Holy fuck! Thats pretty suprising consedering I was hardly driving like a grandma. Is there some huge flaw in my math? This is City driving roughly 12-25 miles a day. Alot of stop go to. No way... something must be off right? Jesus. Haha I love this car!!

[Mgkdrgn]

I've never gotten more than 28mpg in my MS6 (calculated after a single full tank). I always fill up to the top and run to 20-40 miles past the warning light and I usually get between 360-400 miles per tank.

I'm always curious as to whether those claiming better mileage are running on smaller tires...because even the same tire size can differ enough to throw your calculations off.

I'm on the stock tires/rims, and if I'm on a long trip (fairly flat terrain) I can beat 28 by about .5. (example trips, Columbia SC to Washington DC, speeds sustained up to 80 mph, probably avg 70 or so).

On trips to Knoxville from Columbia, SC (over the Smokies) I do about 26 and some change, same speed range.

[chuyler1]

The times I've gotten 27-28 are similar to what you speak of. Highway driving...but staying out of boost as much as possible by using the cruise control between 65-75mph.

[sykopat]

Alright, a little update about my issue.

I just did about 150km (93miles) of highway-only, cruising at less than 3000RPM, more around 2600-2800rpm...
Then, I drove for the whole week, with practically no traffic, mornings and evenings, for about another 200km (124miles), always shifting below 3000RPM.

Right now, I have less than a quarter of tank left, and only 360km (224miles) done so far. I really don't think I'll get to 450km (280miles), even if I drove it the whole time like a 90year old grandma. I really don't get it.

A friend of mine is doing nearly 700km with a full tank when doing mostly highway travelling with his Mazda6i 2.3L, 4cyl. Obviously, he's not as heavy as we are, but still.

Honestly, it seems to be a lot worse than most of the guys here. I'm really thinking about bringing the car in to have it looked at. My best gaz consumption on highway seems to be 18-19mpg...

PS: By the way, my work is about 13miles from my home, with about 5miles city, and 8 miles highway.

[djpatm]

Yeah that seems pretty bad. Get it checked.
I remember when the auto tranny in my parents pathfinder went wacko we were get 24 L/100km. Thats 9 MPG.

It was terrible lol.

I've been driving pretty hard i my speed6 lately and I've done 200 miles on half a tank.

[Igve2shtz]

Sykopat, there are a few other things to consider.
1.) Temperatures -Colder temperatures eat more fuel because the engine runs richer during warm up periods. With fall here, and winter coming, gas mileage typically declines 10-15% in colder weather.
2.) Cold Starts - Do you do lots of short driving? for example, what about going out to lunch during work, say to a Mcdonalds that is only 2 miles away. Short trips that dont allow the engine to fully warm up before shutting off will destroy fuel economy
3.) Shifting - You say you shift before 3000 rpm, but that isnt always the best case. Sometimes shifting early makes you give more gas when you are lower in the RPM range eating some gas. Sometimes shifting at 3500 rpm is better if you are trying to accelerate to keep up with traffic because it prevents the engine from lugging.
4.) Coasting to a stop light with the engine still in gear is a good way to improve mileage. I am not a proponent of constantly downshifting (i think it does more harm than good on the tranny), but if you are doing 50 mph in 5th gear and you see the light ahead is red, just coast in gear, and then put it into neutral around 30 mph. Coasting while in gear causes the injectors to shut off saving increasing gas mileage.
5.) Also, remember in your friends 6i that we have atleast 200 pounds on him, and also, AWD which accounts for around a 10% decrease in fuel economy. And he has a bigger fuel tank. I think regular 6's have around 18 gallons (68 liters) vs. our 15.9 gallons (60 liters)

That is all I can think of now. Take that into account. And good luck on your quest for MPG.