Fuel Efficiency Drop - Page 2 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

stevstevd · 11-05-2013, 02:45 PM

I am not anywhere close to an expert in aerodynamics, or drag. I just did a quick search and posted that article as the first I found... Summed it up fairly well. With my limited knowledge, up until this year, I always thought it was just because I turned the heat on in my car in the winter!

I think the point was more that there is many little bits that have a cumulative effect on fuel economy. The air density was likely one of the least influential.

I would suspect blended fuel to be one of the top reasons for any drop so far. I never even knew about this until I saw this thread. Learn something new everyday. I've noticed a significant drop already (~7.5-10%), car in garage, traffic identical, no idling, tire pressure, and obviously no icy roads contributing to friction, etc.

PS: even though the source was from a Cummings engine website, the person writing it talks about the chart taken from a Honda civic hybrid, and talks about how it relates to his honda accord. And I'd have to agree with the numbers based on all cars i've owned, protege, celica, mazda6, escape, grand vitara, and now a 2014 mazda6.

smbrm · 11-05-2013, 04:14 PM

There is a reason for the extra butane. Because butane boils at lower temperature it is increased in winter to assist with better starting at lower temperatures. Gasoline is made from a range of hydrocarbons that vary in density, boiling point and energy content. The range is tailored for the season. The energy released by burning the lighter molecules generates the heat to burn the heavier molecules. The heaviest part of gasoline boils below the initial boiling point of diesel fuel. While you may think that gasoline explodes in an instant with the firing of the spark plug the burn rate once the light ends are ignited is actually managaed by the progressive combustion from the lightest to heaviest parts. If this isn't managed correctly, you will notice it in vehicle performance.

So gasoline is always seasonally adjusted to optimize its performance. But there are trade offs.

Adding butane in winter isn't new at all and has been a fact since almost forever in the history of gasoline. Limiting it in summer to the degree it is today is newer and dates back to the early 1990's. Before that the only limitation was for performance reasons: too much could prompt vapour lock. Since then it has been further limited in summer for reduced evaporative emissions.

Interestingly butane(which can be in many forms) also has a pretty good octane number, but yes, also less density so less energy content.

So the extra is there for a good reason.

drewbot · 11-05-2013, 04:17 PM

2 tanks of suspect "winter blend" gas: 8 L/100 km (AT)

Previous tanks of summer gas: 7.3 L/100 km (AT)

Almost 10% more fuel consumption over the same commute.

mrdanyo · 11-05-2013, 05:10 PM

I honestly have garbage fuel efficiency because I cant hold back from revving her on corners and swirvy roads.
I can't hold back from revving her anywhere actually. I think I avg 13L/100k. :P

DR 86 · 11-06-2013, 01:51 AM

Wow 7.3L/100km?? Either you do a very high percentage of highway to city driving or drive like a granny lol

drewbot · 11-06-2013, 08:10 AM

Quote:

Originally Posted by DR 86

Wow 7.3L/100km?? Either you do a very high percentage of highway to city driving or drive like a granny lol

My commute to work is 90% highway on the QEW, average speed during rush hour is 85-100 km/h. Couple that with a tall 6th gear on AT = actually decent economy.

Skurj · 11-08-2013, 05:42 PM

Haven't seen the winter gas hit here in the GTA yet.. still getting 600km's on a tank in my winter beater, once winter fuel hits I am lucky to hit 550kms (09 yaris)

I can get 7.3L/100 in the BRZ in the summer on the way to work (5:30am on the 401) but never on the way home...

Captain Stall · 11-13-2013, 11:43 AM

Quote:

Originally Posted by DR 86

Wow 7.3L/100km?? Either you do a very high percentage of highway to city driving or drive like a granny lol

You weren't talking about me, but I'll volunteer I do both. 81% highway driving, and at 90-95 km/h. The gas money is better in my pocket than theirs, plus everyone who goes by me gets a nice long look

pheoxs · 11-13-2013, 11:56 AM

Quote:

Originally Posted by DR 86

Wow 7.3L/100km?? Either you do a very high percentage of highway to city driving or drive like a granny lol

7.3 isn't all that crazy. Cruise at 110km/hr going Calgary to Edmonton and back I averaged 6.2 through the whole tank, even playing around and going on some spirited cruises while there. Managed to hit 700kms to a tank and was pretty impressed.

protpibe · 11-13-2013, 11:57 AM

All vehicles will take a fuel mileage hit when the temperature drops. Others here have already explained the reasons why. My 4-Runner goes down to around 17L/100km in winter

drewbot · 11-13-2013, 12:28 PM

Quote:

Originally Posted by DR 86

Wow 7.3L/100km?? Either you do a very high percentage of highway to city driving or drive like a granny lol

Update: Frosty mornings and idling have gotten me from 8 L/100 km to 8.5 L/100 km...

voyager2285 · 11-13-2013, 12:44 PM

Wow! you guys are good! I'm doing 9.3 L/100km on manual! Although my daily commute consists of 10km round trip city driving to office...

daiheadjai · 11-18-2013, 06:16 PM

~7.9-8L/100km now...
Had been doing better (7.8) in the summer and when I first got the car.

I have bad gas. And winter blend sucks too.

11-05-2013, 05:10 PM	#18
mrdanyo Senior Member Join Date: Mar 2013 Drives: 2014 BRZ Limited (World Rally Blue) Location: Markham, Ontario Posts: 233 Thanks: 56 Thanked 72 Times in 36 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I honestly have garbage fuel efficiency because I cant hold back from revving her on corners and swirvy roads. I can't hold back from revving her anywhere actually. I think I avg 13L/100k. :P __________________ Dan's 2014 WRB Build Thread

11-06-2013, 01:51 AM	#19
DR 86 Senior Member Join Date: Oct 2012 Drives: 2013 FR-S Location: Toronto Posts: 292 Thanks: 17 Thanked 76 Times in 60 Posts Mentioned: 2 Post(s) Tagged: 0 Thread(s)	Wow 7.3L/100km?? Either you do a very high percentage of highway to city driving or drive like a granny lol __________________ Perrin CAI\|Perrin MCB\|P&L header\|Motiv OP/FP\|MXP catback\|Tein Type Flex coilovers\|Eibach F/R sway bars\|GS front strut brace\|Street:PM HC+800/Track:Carbotech XP10\|StopTech slotted rotors/SS lines\|SBC RPF1s\|Street:FK453/Winter:Pirelli SottoZero3/Track:Toyo R888s\|Leg Sport rear spoiler\|EcuTek Tuned\|OEM oil cooler\|4th/F1 brake lights

11-08-2013, 05:42 PM	#21
Skurj Senior Member Join Date: Nov 2012 Drives: SOLD... Location: GTA Ontario Posts: 955 Thanks: 56 Thanked 192 Times in 155 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	Haven't seen the winter gas hit here in the GTA yet.. still getting 600km's on a tank in my winter beater, once winter fuel hits I am lucky to hit 550kms (09 yaris) I can get 7.3L/100 in the BRZ in the summer on the way to work (5:30am on the 401) but never on the way home... __________________ WRB MT BRZ Sport Tech Delivered March 21 2013 Its mine now!! Paid for Mar 2018 and its gone... Sept '18 tho I am sure I will miss it Replaced with 18 50th edition ND

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11-05-2013, 02:45 PM	#15
stevstevd Member Join Date: Mar 2013 Drives: Mazda6 Location: Nova Scotia Posts: 17 Thanks: 0 Thanked 1 Time in 1 Post Mentioned: 0 Post(s) Tagged: 0 Thread(s)	I am not anywhere close to an expert in aerodynamics, or drag. I just did a quick search and posted that article as the first I found... Summed it up fairly well. With my limited knowledge, up until this year, I always thought it was just because I turned the heat on in my car in the winter! I think the point was more that there is many little bits that have a cumulative effect on fuel economy. The air density was likely one of the least influential. I would suspect blended fuel to be one of the top reasons for any drop so far. I never even knew about this until I saw this thread. Learn something new everyday. I've noticed a significant drop already (~7.5-10%), car in garage, traffic identical, no idling, tire pressure, and obviously no icy roads contributing to friction, etc. PS: even though the source was from a Cummings engine website, the person writing it talks about the chart taken from a Honda civic hybrid, and talks about how it relates to his honda accord. And I'd have to agree with the numbers based on all cars i've owned, protege, celica, mazda6, escape, grand vitara, and now a 2014 mazda6.

11-05-2013, 04:14 PM	#16
smbrm Senior Member Join Date: May 2010 Drives: Scion FRS Ht Lva(AT) Location: Alberta Posts: 409 Thanks: 30 Thanked 81 Times in 54 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	There is a reason for the extra butane. Because butane boils at lower temperature it is increased in winter to assist with better starting at lower temperatures. Gasoline is made from a range of hydrocarbons that vary in density, boiling point and energy content. The range is tailored for the season. The energy released by burning the lighter molecules generates the heat to burn the heavier molecules. The heaviest part of gasoline boils below the initial boiling point of diesel fuel. While you may think that gasoline explodes in an instant with the firing of the spark plug the burn rate once the light ends are ignited is actually managaed by the progressive combustion from the lightest to heaviest parts. If this isn't managed correctly, you will notice it in vehicle performance. So gasoline is always seasonally adjusted to optimize its performance. But there are trade offs. Adding butane in winter isn't new at all and has been a fact since almost forever in the history of gasoline. Limiting it in summer to the degree it is today is newer and dates back to the early 1990's. Before that the only limitation was for performance reasons: too much could prompt vapour lock. Since then it has been further limited in summer for reduced evaporative emissions. Interestingly butane(which can be in many forms) also has a pretty good octane number, but yes, also less density so less energy content. So the extra is there for a good reason.

11-05-2013, 04:17 PM	#17
drewbot ( ͡° ͜ʖ ͡°) Join Date: Sep 2013 Drives: '13 Whiteout FR-S A/T Location: Mississauga, ON Posts: 1,996 Thanks: 1,985 Thanked 1,452 Times in 752 Posts Mentioned: 36 Post(s) Tagged: 1 Thread(s)	2 tanks of suspect "winter blend" gas: 8 L/100 km (AT) Previous tanks of summer gas: 7.3 L/100 km (AT) Almost 10% more fuel consumption over the same commute.

11-13-2013, 11:57 AM	#24
protpibe Senior Member Join Date: Oct 2013 Drives: 4-Runner Sport - 13' BRZ SportTech Location: Winnipeg Posts: 1,395 Thanks: 253 Thanked 839 Times in 459 Posts Mentioned: 18 Post(s) Tagged: 0 Thread(s)	All vehicles will take a fuel mileage hit when the temperature drops. Others here have already explained the reasons why. My 4-Runner goes down to around 17L/100km in winter

11-13-2013, 12:44 PM	#26
voyager2285 Member Join Date: Jun 2012 Drives: WRB BRZ Location: Vancouver, BC Posts: 85 Thanks: 71 Thanked 15 Times in 11 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Wow! you guys are good! I'm doing 9.3 L/100km on manual! Although my daily commute consists of 10km round trip city driving to office...

11-18-2013, 06:16 PM	#27
daiheadjai Senior Member Join Date: Feb 2012 Drives: 2003 S2000, 2008 Fit Location: Toronto, ON, Canada Posts: 1,990 Thanks: 2,584 Thanked 1,154 Times in 688 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	~7.9-8L/100km now... Had been doing better (7.8) in the summer and when I first got the car. I have bad gas. And winter blend sucks too.

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