WRX sedan vs hatch MPG...just curious

Hey guys

So I've been racking my brain over this one for weeks, but can't seem to understand it. I have a 2013 WRX hatch (Limited) and my friend has a 2012 WRX sedan (base + fog lights).

Similarities: We both run on the same tires (OEM Dunlop in the summer, Dunlop WinterMaxx in the winter) at the same psi (34 cold). We have extremely similar driving styles (2-3 hard pulls during my 10 minute commute, otherwise just cruising between 70-75 mph) and extremely similar commutes (90% highway). Both cars are Cobb stage 1+ (intake+ecu flash).

Differences: His car has 17k miles, mine has 7k miles. His has an upgraded TB to IC pipe, but otherwise stock like mine. I have an aggressive alignment compared to stock (0 toe all around, max camber on stock hardware up front) but otherwise all suspension/brake stuff is stock for both of us.

Despite these slight differences, his car seems to consistently get 3-4mpg better than mine at all times, under all driving conditions. I can't seem to figure out why. We have 99% the same engine setups, disregarding the TB-IC pipe (installed mostly as a preventative measure, given that the stock ones fail often under even stock boost pressures). The only things I can think of are aero differences (hatch vs sedan) and weight (52 lb difference in his favor), but I cannot imagine that these two things can account for that much MPG...can they?

Any insight would be greatly appreciated.

Edit: I should add location, in case it makes a difference. He lives in Buffalo, NY...I live in Akron, OH

Aerodynamically, the hatch has less drag and should be slightly more fuel-efficient (and have a slightly higher top speed, assuming drag-limited). In theory, at least. But not enough that you would be able to tell.

Just because you have "similar driving styles" doesn't really mean much anyhow. You may think you do, but MPG can be heavily affected by just being 10% heavier on the throttle, or driving mph faster or slower on a long highway cruise.

Weight would not be an issue unless you're doing constant stop-and-go.

What "actual" MPG do you get? (and I mean, calculated on how much gas you fill up with vs. how many miles you went.....not using the trip computer, which is not very accurate). I have an 09 with AP Stage 1 as well and my "typical" mpg for my commuting is about 24mpg (probably 50-50 city/highway), about 27-28 mpg for highway cruising at 75mph for long distances, and I've gotten just a shade under 30 a few times in highway traffic going 55-60, while rolling behind trucks/SUVs for long distances (really reduces drag). All of this also with SP Sport 01 tires. My mileage doesn't change much in the winter with Wintersport 3D tires.

All that said, you really can't compare MPG numbers between two different people in different places any more than you can compare dyno numbers from different shops and different dynos. The only way you could have a valid comparison is if you drove his car for a few weeks and he drove yours, and then see what numbers you get.

Other than that, I wouldn't worry about. Driving style,.

irish44j

Your avg mpg is consistent with what my friend is getting, although he claims he is now seeing up to 30+ on the winter tires (they are 215/50/16). I, however hard I try (and I try hard...I was a frugal student for many years before I got my hands on this car...old habits die hard), can only seem to manage a MAXIMUM of 22mpg on my daily 90% highway commute, and 25mpg on long trips (Ohio to NY, cruise no faster than 74 mph). I can't seem to figure it out...and these are mostly mpg figures I calculate by hand, not using the trip computer. My friend and I spend a lot of time together and I can say that his driving style is extremely similar to mine, although I suppose you're right about even the small differences changing the bottom line...

Trip computer reads about 2mpg high in my experience. So if your friend is using that, that could explain why his are better.

He is not seeing 30+ unless he is doing full tanks going downhill at 55mph the entire time. Definitely not if he's doing ANY city driving or going over 60mph ever. WRX really starts burning some gas at the RPMs required over 60mph. He may be a good friend, but he either has rose-colored glasses, or he's simply exaggerating.

How is he calculating his mpg? 30+ mpg for a wrx? I am a subaru guy and I am extremely skeptical of that number.

I am thinking that a mpg contest with rules and 3rd party verification of his mpg is in order. And of course the loser suffers some sort of public humiliation.

Looking back through my fuel log for 90k miles on this car (including autocrosses, snow days, and other hoonery), I'd say over the entire life of my car I have gotten in the vicinity of 23.5 mpg total, FWIW. One day maybe I'll calculate it for sure, but my typical commuting tank is around 24, and I've gotten some 22's here and there (heavy traffic, lots of local stuff, etc).

I have never had a tank get LESS than 20mpg (calculated) during the life of this car. Even tanks I did autocrosses on part of.

one last thing: my car is an 09, so its a bit "slicker" aero than the widebody WRXs and has less frontal area on the front clip. So I would guess that helps out in MPG for me vs. you, since IIRC the '12 is a widebody, right?

Hmm I misspoke on the 30+ mpg...that was a number that the trip computer showed upon resetting the trip meter and going immediately back to long haul highway cruising. Still, he gets the average 27-28 long trip and 23-24 commuting that you mentioned for your car.

My issue is that since I got this car, it seems to burn more than the average that you are mentioning for yours. Far more. I calculate my MPG with every tank and usually just disregard the trip meter...even still, my avg tank mpg fluctuates between 19-21 at best. I had one tank come close to 22mpg. That mileage suffered greatly with an autocross session per tank. The trip meter actually often shows me pretty low numbers...16.5 at times, without driving it extraordinarily hard. I got the car brand new, had a moderate-aggressive break in procedure until 700 miles and its only needed one oil change thus far. The car has only seen the Cobb stage 1 and intake, as mentioned earlier. I cannot imagine that my alignment alone is a factor. As far as I can tell, the engine is running smooth and well, and all datalogs have been perfect. Any ideas?

Cliff notes: My friend's car gets the mileage you guys seem to get. Mine does not.

Oh, and yes both my friend and I have the "widebody" version

nope, can't seem to think of anything, unless you guys are using different gas (ethanol % can affect mpg, for instance). Alignment can have an effect, but if you're not getting any crazy wear on your tires, it wouldn't be more than 1mpg.

Do you have a boost gauge? If not, go get one, and then use it to drive a full tank OUT of boost (I do that when I'm low on gas). You may just have a heavy foot and not know it.

Alternately, you could try the AP "economy" map and see how that does, IDK.

Or you could have it dyno'd with A/F and see if your car is running excessively rich for some reason.

I use the indicated boost on the accessport. I suppose I'll try to drive one tank outta boost and see how it does, although I suppose on winter gas and tires it won't be the number I'd be able to see most of the year.

Or I'll need to get my right foot remade from dry carbon...hmm....

I appreciate the input btw. If anyone else has ideas, I'm all ears.

Most fuel mileage is affected by the drivers right foot.(;) Switch cars and see what happens. Unless they are driven on identical routes you can't compare.

iceracer wrote: Most fuel mileage is affected by the drivers right foot.(;) Switch cars and see what happens. Unless they are driven on identical routes you can't compare.

unless you ar driving 40 miles to work and havr cruise control on going 80, at which case I get 23 mpg in the sedan

My wifes car is a 2012 Accord, and I always seem to achieve at or above the manufacturer stated claims for mileage. In fact, I've been like that with every previous car I've owned...89 Volvo 740GL, 95 Camry, 01 Highlander, 99 Prelude...but this car it seems like no matter what I do, I can't at least match what others are getting. The few owners who've posted in this thread alone seem to get way better than I do even when I BABY the car. Plus, the car is brand new, so I'm beginning to get paranoid...

GAH.

My 2013 5door gets 19-20 in town 26 highway at 72 and has averaged 23. Has 21000 miles on it.

Hmmm...that makes me feel a bit better...have you taken any long road trips where it achieved better, and does it have any kind of ECU tweaks?

Stock and the 26 highway is on long trips.

Hmmm yeah that sounds about consistent with mine...Now I'm just wondering if its a 2013 thing...all of the other people who've posted in this thread thus far have noted higher avg gas mileage, including my friend with a 2012 widebody. I was under the impression there were no changes between 2012 to 2013?

Wagons are always LESS aero than their sedan counter parts because of the sharp cut off at the rear. Usually about .01-.02 Cd. That aside, unless you two guys are driving the exact same route at the same time it is difficult to compare. A couple of additional traffic lights could make a big difference. Driving style will also make a big difference.

Do you both use the same motor oil/weight?

Yes, same motor and Subaru OEM oil. And yes, I was also under the impression that the hatch suffers a bit from a drag perspective.

The biggest single variable when it comes to fuel mileage is how the car is driven by the driver. That alone usually makes it difficult to compare two cars driven by two different drivers. Driving style alone can make a significant difference especially around town. Hwy - as long as speed is consistent between the two drivers - less differences.

I had an '09 WRX - only had the SPT cat back on it - otherwise stock. I kept a close eye on mileage over the 24k miles I incurred until the rod bearings let go. Pretty consistently got 20-21 mpg in fairly heavy city driving. Hwy mileage varied quite a bit depending on speed, ambient temp and how much other traffic was on the road. Running 75-80 in colder temps without much other traffic ("draft") - 25-27 mpg. Running 65-70 in spring/fall with more traffic ("draft") - 29-32 mpg. There's you another data point.

Also found that the mileage showed by the car's computer consistently overstated mpg by 1-2 mpg in the city; was fairly accurate on the highway.

I'm gonna go with a mix of alignment(0 toe static=slight toe out rolling) and driver.

Kenny, can the toe change you refer to be compensated for at my next alignment? Like toe in a bit on purpose static? sorry if this is a dumb question...

Hmm based on the responses it, it still seems like there is a huge variance between the mileage people are achieving. Of course, all of these cars have different mods and are driven in different places...not to mention, some are the "narrow" body and some are the wide body. Perhaps I am being too paranoid about there being something wrong with my car lol