Welcome to the North American Subaru Impreza Owners Club Monday November 12, 2018
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Subaru Models > Impreza Forum

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 04-18-2018, 01:06 PM   #1
BlueBellThunder
Scooby Newbie
 
Member#: 484592
Join Date: Apr 2018
Default Gas mileage

Think I may have been cheating on gas. According to the car I got 25 mpg. When I filled it up it was 23. I reset the trip meter after my first fill up. It took 15.3 gallons. If Iím not mistaken the capacity is 15.9. The car said I was 10 miles to empty. I know some cars have a up to a 2 gallon reserve. My question is do these have less? My first fill up 10 days ago at the same station different pump was 13.5 gallons and the car had 50 miles to empty. Itís a Sunoco station, Iíve never used them before, always went to wawa and got regular. Wawaís regular is 92. Iím assuming thatís god enough, but they actually charge more. But if this Sunoco is cheating me, Iíll look elsewhere. This is a new car and only my second fill up, itís a 2018 WRX CVT.

Thanks for letting me rant.
* Registered users of the site do not see these ads.
BlueBellThunder is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 04-18-2018, 02:02 PM   #2
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

Highly unlikely you're being cheated.

Miles to empty on any car is a rough estimate, pessimistic by design and shouldn't be relied upon.

Also, gallons to full can vary based on the incline of the ground you're fueling on.

I believe gas stations are subject to random testing by most states and fined heavily if found to be cheating. If you really want to know the truth, fill a container you can later inspect.
Commander Keen is online now   Reply With Quote
Old 04-18-2018, 03:29 PM   #3
BlueBellThunder
Scooby Newbie
 
Member#: 484592
Join Date: Apr 2018
Default

I forgot to mention I live in NJ, were sometimes gas stations get caught, we are probably higher than the national average. Not that you see this on the news on a regular occurrence. Iíll have to read the manual, to see if this car has a small reserve.
BlueBellThunder is offline   Reply With Quote
Old 04-18-2018, 04:40 PM   #4
Commander Keen
Scooby Specialist
 
Member#: 319157
Join Date: May 2012
Chapter/Region: MAIC
Vehicle:
2012 Impreza 4DR 5MT

Default

There is no discrete "reserve", just a single tank.

Letting the fuel get that low is a bad idea for a number of reasons.

Quote:
I forgot to mention I live in NJ, were sometimes gas stations get caught, we are probably higher than the national average.
Your state is the only one which prevents you from operating the pump. Odd coincidence.

Last edited by Commander Keen; 04-18-2018 at 04:46 PM.
Commander Keen is online now   Reply With Quote
Old 04-22-2018, 08:29 PM   #5
EricP350
Scooby Newbie
 
Member#: 468253
Join Date: May 2017
Default

87 octane is all you need, any more is pouring good money down the drain. Higher octane provides no benefits in modern computer controlled vehicles.
EricP350 is offline   Reply With Quote
Old 05-12-2018, 09:31 PM   #6
BlueBellThunder
Scooby Newbie
 
Member#: 484592
Join Date: Apr 2018
Default

Quote:
Originally Posted by EricP350 View Post
87 octane is all you need, any more is pouring good money down the drain. Higher octane provides no benefits in modern computer controlled vehicles.
The owners manual on the 2018 WRX says itís mandatory to put at least 91 in the car.
BlueBellThunder is offline   Reply With Quote
Old 05-14-2018, 08:17 PM   #7
BlueBellThunder
Scooby Newbie
 
Member#: 484592
Join Date: Apr 2018
Default

I got gas again today at a different station same result, car says I got 24.3 mpg, but the miles I drove and the amount of gas it took says I got 22.3 mpg. The chances of 2 gas stations being shifty are unlikely. So I guess the cars computer isn’t accurate. No big deal, if I was being cheated, now that would be a big deal.
BlueBellThunder is offline   Reply With Quote
Old 05-14-2018, 08:24 PM   #8
DieselDorf
Scooby Newbie
 
Member#: 454773
Join Date: Sep 2016
Chapter/Region: MWSOC
Location: Traverse City, MI
Vehicle:
2012 Impreza Sport
Pearl White

Default

I've heard a few people mention the cars computer is off based on hand calculations as well, mine included. Not by much though
DieselDorf is offline   Reply With Quote
Old 05-15-2018, 01:53 PM   #9
Harriska2
Scooby Newbie
 
Member#: 464377
Join Date: Mar 2017
Location: Corvallis, OR
Vehicle:
2017 Impreza 5 Dr

Default

Quote:
Originally Posted by Commander Keen View Post
Your state is the only one which prevents you from operating the pump. Odd coincidence.
Oregon is another state. My gas mileage based on gallons to fill up and miles driven have been stable since after the first 4 or 6,000 miles on our 2017 impreza.
Harriska2 is offline   Reply With Quote
Old 06-04-2018, 01:33 AM   #10
joshrfrank
Scooby Newbie
 
Member#: 369823
Join Date: Oct 2013
Location: Oregon
Vehicle:
2018 WRX Premium
WR Blue Pearl

Default

Quote:
Originally Posted by BlueBellThunder View Post
I got gas again today at a different station same result, car says I got 24.3 mpg, but the miles I drove and the amount of gas it took says I got 22.3 mpg. The chances of 2 gas stations being shifty are unlikely. So I guess the cars computer isnít accurate. No big deal, if I was being cheated, now that would be a big deal.


It also depends on how you are driving. I also have a 2018 WRX and when I drive easy, I get like 28 mpg but once I run it hard, thatís when it drops to like 23 mpg.
joshrfrank is offline   Reply With Quote
Old 06-04-2018, 01:55 PM   #11
Scooby Coupe
Scooby Newbie
 
Member#: 2746
Join Date: Oct 2000
Chapter/Region: MWSOC
Location: Blackberry Township, Illinois
Vehicle:
2017 WRX Premium
Dark Gray Metallica

Have a Nice Day?

Quote:
Originally Posted by DieselDorf View Post
I've heard a few people mention the cars computer is off...
Yeah, mine is consistently over-stated by 2.0 - 2.5 mpg. Not an issue for me, though.
Scooby Coupe is offline   Reply With Quote
Old 06-04-2018, 08:56 PM   #12
DaSubie22
Scooby Newbie
 
Member#: 480715
Join Date: Jan 2018
Default Gas Mileage

I have a '15 WRX mt stock and my calculated MPGs are always 1.5-2.5 mpg lower than the computer. I have noticed when my driving is "less spirited" it's on the lower side 1.5 off and more aggressive driving seems to make the difference bigger.
DaSubie22 is offline   Reply With Quote
Old 06-04-2018, 09:01 PM   #13
DaSubie22
Scooby Newbie
 
Member#: 480715
Join Date: Jan 2018
Default Gas Mileage

Quote:
Originally Posted by joshrfrank View Post
It also depends on how you are driving. I also have a 2018 WRX and when I drive easy, I get like 28 mpg but once I run it hard, thatís when it drops to like 23 mpg.
Not to burst your bubble or anything, but I think if you do a manual calculation of your fuel, you will notice you are not getting that great of gas mileage. I reset trip B at each fill up (trip A I use for oil changes) and when I go to fill up again, I divide the miles by the gallons of gas put in. That mpg is always lower than what the computer says. I just drove like a grandma and got 24.9 mpgs (manually calculated). My computer said 26.7 mpg.
DaSubie22 is offline   Reply With Quote
Old 06-20-2018, 03:36 AM   #14
Azsubi
Scooby Newbie
 
Member#: 487405
Join Date: Jun 2018
Default

Quote:
Originally Posted by BlueBellThunder View Post
The owners manual on the 2018 WRX says itís mandatory to put at least 91 in the car.
I wouldn't put anything under 91
Azsubi is offline   Reply With Quote
Old 07-15-2018, 04:56 PM   #15
quidnatch
Scooby Newbie
 
Member#: 488174
Join Date: Jul 2018
Default

Quote:
Originally Posted by EricP350 View Post
87 octane is all you need, any more is pouring good money down the drain. Higher octane provides no benefits in modern computer controlled vehicles.
Not true. While modern cars will retard timing to adjust for lower octane it will reduce the power output by doing so. On most cars its not a big deal, maybe a few up, and people won't notice. However, in turbo cars like the WRX, GTI, etc it can be as much as a 20hp loss. Go to Mazdas website and look at the 2018 Mazda 6. It shows different numbers for 87 and 91

FYI. I work in the industry and can say 100% that all car testing for MPG, Up, etc is done on higher octane gas. Even if it only calls for 87.
quidnatch is offline   Reply With Quote
Old 07-15-2018, 04:59 PM   #16
quidnatch
Scooby Newbie
 
Member#: 488174
Join Date: Jul 2018
Default

The mileage calculator on this car is optomistic and thats being polite. To say it lies is more accurate. In order to determine your MPG you must do it manually. Use something like fuelly if you would like to keep a record.

I show 25.7 lifetime and usually get the computer to read about 29 per tank on my new commute. I am lucky to get 25 irl when calculating manually.
quidnatch is offline   Reply With Quote
Old 07-16-2018, 12:13 PM   #17
lymphomaniac
Scooby Specialist
 
Member#: 334451
Join Date: Oct 2012
Chapter/Region: VIC
Location: YVR
Vehicle:
2018 WRX Sport CVT
CBS

Default

The MPG meter (or here in Canada, the fuel consumption meter) is normally generous by about 10%. I had it happen with my 2013 Impreza, and it's doing the same with my 2018 WRX. I hear you can get it re-dialed by the techs to something more representative of real life conditions, but ymmv (pun intended).
lymphomaniac is offline   Reply With Quote
Old 07-29-2018, 02:38 PM   #18
WRX04Devotion
Scooby Newbie
 
Member#: 488667
Join Date: Jul 2018
Chapter/Region: International
Location: Europe
Vehicle:
2004 Impreza WRX GD
Blue Mica 02C

Default

The only reliable way how to calculate mileage is manually, like others say here. On my daily commuter I do it like this:

ē When I arrive at gas station, I write down (or take a photo) of the fuel gauge, estimated remaining miles on current tank and the number of actual driven miles in trip meter since last gas station stop.
ē Then I get X gallons of petrol which I can get for 40$ and also keep the bill, where the exact amount of petrol is printed.
ē Before I leave gas station, I reset the trip meter.
ē At home I shovel all these numbers in spreadsheet, which calculates MPG (from traveled distance / purchased petrol from previous gas station visit) and tracks petrol price. I know, there are some apps for it, but I like to set up my own charts, where I can eventually extrapolate even more data.
WRX04Devotion is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 10:13 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.