MPGs...Am I seeing things?!

[3VOM]

So when I first got the 135i I wasn't paying attention and noticed that my full tank of as seemed to go empty pretty quick! I assumed it must be because I was driving it too hard too much! . So i started monitoring my gas mileage the next couple full tanks...driving very conservitively, at half tank I would be at about 130 miles. Total avg on those two full tanks was about 270ish. Now what's interesting is the current tank of gas has me at about 155 miles at half tank and I have been driving pretty hard and in sport most of the time! So what's the deal? Does this make any sort of sense? The only other thing that I did differently is where I filled up. The first 2 fill ups were done at Costco and the most recent at Chevron...both 91 (highest grade available in the Phoenix area). Now I've heard rumors of Costco gas being less superior yada yada...but a good friend of mine that owns like 12 gas stations said that that was a myth. Thoughts? I guess the one thing I do know is I will just drive the car harder in sport mode ALL THE TIME!! haha

J

[Simsims]

well
the 135 does have a TINY tank. It's not really a gas guzzler unless you stomp it all the time.

you can easily achieve 27+mpg on the highway. But in the city......... I see 15mpg not impossible, LOL.

[3VOM]

Originally Posted by Simsims

well
the 135 does have a TINY tank. It's not really a gas guzzler unless you stomp it all the time.

you can easily achieve 27+mpg on the highway. But in the city......... I see 15mpg not impossible, LOL.

Yes...this gas tank is tiny! I can hold more gin and tonics in my belly than this car can hold gas in it's tank! Haha

[JimD]

There are a lot of factors that influence mpg. I keep a little notebook in each of my cars where I write down the mileage and gallons each time I buy gas. I enter the data in a spreadsheet and review it periodically. The display in our cars is optimistic, my actual mileage is always lower than my cars says. I haven't detected many strong trends but I know the mileage for the tank when I run an autocross is always low. If I make a long trip it will be higher. Mileage for commuting through 10 stop lights is lower than crusing on the highway. I've also noticed that crusing 70+ in my bimmer gets me much better mileage than crusing the same speed in my SUV.

But any sort of correlation suggesting pushing the gas pedal harder results in higher mileage I think would be wrong. It may not hurt mileage as much as you might think it would, perhaps, but if your mileage increased while accelerating harder I think there was also something, like some sustained highway crusing, that offset the hard acceleration.

Jim

[3VOM]

Originally Posted by JimD

It may not hurt mileage as much as you might think it would, perhaps, but if your mileage increased while accelerating harder I think there was also something, like some sustained highway crusing, that offset the hard acceleration.

Jim

good point. I'll still have to keep trying my drive harder experiment!

[Simsims]

Originally Posted by 3VOM

Yes...this gas tank is tiny! I can hold more gin and tonics in my belly than this car can hold gas in it's tank! Haha

[3VOM]

Originally Posted by Simsims

http://t3.gstatic.com/images?q=tbn:A...ayc7IT6TZ3MQuy

Don't know how to post images from my iPad...but enjoy.

[Tom K.]

Originally Posted by JimD

There are a lot of factors that influence mpg. I keep a little notebook in each of my cars where I write down the mileage and gallons each time I buy gas. I enter the data in a spreadsheet and review it periodically. The display in our cars is optimistic, my actual mileage is always lower than my cars says.
Jim

Jim, I also record my gas consumption (partial business use) and have discovered that the OBC error varies from car to car with the overall trend towards more accuracy:

'99 328i - 9% optimistic
'03 Z4 3.0 - 6% optimistic
'07 328iT - 2% optimistic
'08 128i - accurate to within 0.5% - after correcting for a 1.5% pessimistic odometer.

Tom

[ken1137]

Originally Posted by 3VOM

http://t3.gstatic.com/images?q=tbn:A...ayc7IT6TZ3MQuy

Don't know how to post images from my iPad...but enjoy.

Yep, that tank is bigger than the 1'ers

[BrokenVert]

Originally Posted by Tom K.

Jim, I also record my gas consumption (partial business use) and have discovered that the OBC error varies from car to car with the overall trend towards more accuracy:

'99 328i - 9% optimistic
'03 Z4 3.0 - 6% optimistic
'07 328iT - 2% optimistic
'08 128i - accurate to within 0.5% - after correcting for a 1.5% pessimistic odometer.

Tom

I've found it to be between 1 and 1.5% - to add to your correlations

[fs454]

So this tank is what, 13ish gallons? What's the highest amount of miles you guys have gotten per tank on trips? I know it must be around 200-250 for a mix of city/spirited driving but is it possible to achieve 350 miles per tank pure highway?


I'm stepping into a 135i soon and hope it isn't TOO much worse than my current car.

[3VOM]

Originally Posted by fs454

So this tank is what, 13ish gallons? What's the highest amount of miles you guys have gotten per tank on trips? I know it must be around 200-250 for a mix of city/spirited driving but is it possible to achieve 350 miles per tank pure highway?


I'm stepping into a 135i soon and hope it isn't TOO much worse than my current car.

I had an A3 3.2 and I'd say the gas mileage will be pretty close. I think 280ish pure highway is doable. I also used to live in MA...pretty close to where you live...Peabody. Right down the ole 128.

[Guildenstern]

Originally Posted by 3VOM

Now I've heard rumors of Costco gas being less superior yada yada...but a good friend of mine that owns like 12 gas stations said that that was a myth. Thoughts? I guess the one thing I do know is I will just drive the car harder in sport mode ALL THE TIME!! haha

J

Chevron and Shell are Top Tier Detergent gasoline, the stuff BMW recommends http://www.toptiergas.com/

While it's true all the gas comes from the same refinery distribution. What shell or Chevron does with it before it ends up in your tank, vs what costco or GetGo do is a difrent story.

Cheap gas usualy has little to no cleaning additives, may not be filtered or dried as thoroughly prior to showing up at the station, and most importantly cheap gas is "watered" down with the maximum government allowance of ethanol which is basically the High Fructose Corn Syrup of gasoline. (which coincidentally comes from corn!)

Ethanol retains water (un-like petrol it's water soluable) so it causes corrosion and damage to seals designed to only deal with petro products, the water can come out of solution due to temperature change and as the ethanol percentage changes and leave a puddle of water in your tank, and overall ethanol has lower energy. 1 gal of Ethanol has less energy in it than one gallon of un-blended gasoline. Gasoline has about 33.41 kWh per gallon of energy, whereas DRY ethanol has only 22.27 kWh per Gallon (it has even less energy per volume when there's water in solution with it.) At the federal max of reformulated ethanol blend (the cheap stuff *looking at you sunoco*) you end up with a liquid that only has 98.14% of the total energy of pure gasoline. And that's before you take into account the variations caused by different specific heats and how that effects engine efficiency etc... http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

Lower energy, and adverse engine efficiency properties means you need to burn more fuel to get the same performance. You may not notice it, but even to maintain freeway speed you are a little deeper on the throttle, and the engine is running a little richer. That adds up to lower mileage.

SCIENCE!!

[3VOM]

Originally Posted by Guildenstern

Chevron and Shell are Top Tier Detergent gasoline, the stuff BMW recommends http://www.toptiergas.com/

While it's true all the gas comes from the same refinery distribution. What shell or Chevron does with it before it ends up in your tank, vs what costco or GetGo do is a difrent story.

Cheap gas usualy has little to no cleaning additives, may not be filtered or dried as thoroughly prior to showing up at the station, and most importantly cheap gas is "watered" down with the maximum government allowance of ethanol which is basically the High Fructose Corn Syrup of gasoline. (which coincidentally comes from corn!)

Ethanol retains water (un-like petrol it's water soluable) so it causes corrosion and damage to seals designed to only deal with petro products, the water can come out of solution due to temperature change and as the ethanol percentage changes and leave a puddle of water in your tank, and overall ethanol has lower energy. 1 gal of Ethanol has less energy in it than one gallon of un-blended gasoline. Gasoline has about 33.41 kWh per gallon of energy, whereas DRY ethanol has only 22.27 kWh per Gallon (it has even less energy per volume when there's water in solution with it.) At the federal max of reformulated ethanol blend (the cheap stuff *looking at you sunoco*) you end up with a liquid that only has 98.14% of the total energy of pure gasoline. And that's before you take into account the variations caused by different specific heats and how that effects engine efficiency etc... http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

Lower energy, and adverse engine efficiency properties means you need to burn more fuel to get the same performance. You may not notice it, but even to maintain freeway speed you are a little deeper on the throttle, and the engine is running a little richer. That adds up to lower mileage.

SCIENCE!!

Wow! I have no idea what I just read but ok...no more Costco gas for me. Haha

[fs454]

Originally Posted by Guildenstern

Chevron and Shell are Top Tier Detergent gasoline, the stuff BMW recommends http://www.toptiergas.com/

While it's true all the gas comes from the same refinery distribution. What shell or Chevron does with it before it ends up in your tank, vs what costco or GetGo do is a difrent story.

Cheap gas usualy has little to no cleaning additives, may not be filtered or dried as thoroughly prior to showing up at the station, and most importantly cheap gas is "watered" down with the maximum government allowance of ethanol which is basically the High Fructose Corn Syrup of gasoline. (which coincidentally comes from corn!)

Ethanol retains water (un-like petrol it's water soluable) so it causes corrosion and damage to seals designed to only deal with petro products, the water can come out of solution due to temperature change and as the ethanol percentage changes and leave a puddle of water in your tank, and overall ethanol has lower energy. 1 gal of Ethanol has less energy in it than one gallon of un-blended gasoline. Gasoline has about 33.41 kWh per gallon of energy, whereas DRY ethanol has only 22.27 kWh per Gallon (it has even less energy per volume when there's water in solution with it.) At the federal max of reformulated ethanol blend (the cheap stuff *looking at you sunoco*) you end up with a liquid that only has 98.14% of the total energy of pure gasoline. And that's before you take into account the variations caused by different specific heats and how that effects engine efficiency etc... http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

Lower energy, and adverse engine efficiency properties means you need to burn more fuel to get the same performance. You may not notice it, but even to maintain freeway speed you are a little deeper on the throttle, and the engine is running a little richer. That adds up to lower mileage.

SCIENCE!!

I've always heard that Sunoco is one of the top tiers of fuel quality...all the guys dynoing around here swear by the stuff. Hmm.

[Zeros and ones]

Originally Posted by Guildenstern

Chevron and Shell are Top Tier Detergent gasoline, the stuff BMW recommends http://www.toptiergas.com/

While it's true all the gas comes from the same refinery distribution. What shell or Chevron does with it before it ends up in your tank, vs what costco or GetGo do is a difrent story.

Cheap gas usualy has little to no cleaning additives, may not be filtered or dried as thoroughly prior to showing up at the station, and most importantly cheap gas is "watered" down with the maximum government allowance of ethanol which is basically the High Fructose Corn Syrup of gasoline. (which coincidentally comes from corn!)

Ethanol retains water (un-like petrol it's water soluable) so it causes corrosion and damage to seals designed to only deal with petro products, the water can come out of solution due to temperature change and as the ethanol percentage changes and leave a puddle of water in your tank, and overall ethanol has lower energy. 1 gal of Ethanol has less energy in it than one gallon of un-blended gasoline. Gasoline has about 33.41 kWh per gallon of energy, whereas DRY ethanol has only 22.27 kWh per Gallon (it has even less energy per volume when there's water in solution with it.) At the federal max of reformulated ethanol blend (the cheap stuff *looking at you sunoco*) you end up with a liquid that only has 98.14% of the total energy of pure gasoline. And that's before you take into account the variations caused by different specific heats and how that effects engine efficiency etc... http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

Lower energy, and adverse engine efficiency properties means you need to burn more fuel to get the same performance. You may not notice it, but even to maintain freeway speed you are a little deeper on the throttle, and the engine is running a little richer. That adds up to lower mileage.

SCIENCE!!

finally.. someone that understands gas. +1.

[1911A145]

I dont even know how much gas my car uses. I just fill it up with top tier fuel and ride out. if i beat on it all the time or drive it easy on the highway im usually always between 310-360 on the trip meter for a full tank.

[BrokenVert]

Originally Posted by fs454

So this tank is what, 13ish gallons? What's the highest amount of miles you guys have gotten per tank on trips? I know it must be around 200-250 for a mix of city/spirited driving but is it possible to achieve 350 miles per tank pure highway?


I'm stepping into a 135i soon and hope it isn't TOO much worse than my current car.

Its 14 gallons - farthest ive managed on a tank is about 450 miles

[Tom K.]

Originally Posted by Guildenstern

...and most importantly cheap gas is "watered" down with the maximum government allowance of ethanol

Maybe that's true in Ohio, but ALL gas In the DC~Baltimore area, including top tier, has been laced with 10% ethanol for a couple of years - so I'll continue to save 20 to 30 cents per gallon with the off brand stuff. And having used off brand 93 octane for nearly 15 years in 5 Bimmers and 2 Beemers with no engine problems, top tier seems to me to be little more than a marketing ploy.

As a matter of fact, on a recent trip through Alabama and Mississippi, the only stations advertising ethanol free gas were non top tier outlets.

Tom

[3VOM]

Originally Posted by BrokenVert

Its 14 gallons - farthest ive managed on a tank is about 450 miles

Wow! Tell me that's all highway cruising miles!

[BrokenVert]

Originally Posted by 3VOM

Wow! Tell me that's all highway cruising miles!

Yep. Settle in at 75 with the top down and watch the mileage pour in!

[Guildenstern]

Originally Posted by fs454

I've always heard that Sunoco is one of the top tiers of fuel quality...all the guys dynoing around here swear by the stuff. Hmm.

Well it's got brand loyalty (Official Brand of Nascar!) and they are one of the few distributors of over 100 octane. But it does not fall into the top tier either because it doesn't qualify, or more likely they didn't waste the money to be certified as a top tier.

I do know in Ohio anyways (thanks for pointing that out Tom K. I thought this was all at the fed level but I guess it's at the market level) that Sunoco has the "contains x% ethanol" sticker on the pumps, and really the only place ethanol belongs is in my belly, not my gas tank.