The STI specifically returns poor fuel economy.

Several reasons for this:
1. Gearing - the STI is geared aggressively and not for highway driving. That 6th cog is even a bit shorter than the 5th gear in the 2L WRX.
2. Driveline losses - did you know the STI 6MT weighs about 2.5x as much as the 5MT in the 2L WRX? The engine has to spin all of that mass all of the time. Much larger gears, heavy Torsen/Torsen-like diffs at all axles, etc. You pay for this robustness at the pump.
3. Tires - The STI shipped with wider tires in base models vs. the WRX. In the past, that also included stickier rubber. Both of these negatively impact economy.
4. Displacement - No getting around this - the EJ25_ is 25% larger displacement than the EJ205 in your car. Since it isn't geared any more efficiently (point #1) this just means it consumes more fuel due to pumping losses.

My 2L WRX would routinely get between 24 and 27mpg measured at the pump. My STI has never exceeded 23. The FA20 is a more efficient powerplant than even the older EJ205, but it's also being asked to move a much larger car than your 2004.

Also keep in mind perspective. To you, 25mpg is great. To most others, it's middling at best. We live in a world where a 5500lb Ford Explorer gets 30+ mpg on the highway.

 

Appreciate the detailed response as I cont. learning more about the platform! That’s wild the weight delta in the 5 v 6 speeds. Also glad to know someone who (previously) owned a similar gen got the same mileage.

Absolutely all relative. My wife’s vehicle gets 12-14, and my other stuff was always 15-18. Anything starting w a “2” is amazing to me lol. But to my buddy who has only owned Camry’s (non car guy) he thinks I’m crazy

 

Good for you. I have a 2020 and rarely take a spirited drive...mostly within 5 mph of the speed limit, and I am experiencing only 21 to 22 mpg.

 

How short are your trips? Short (<5miles) commutes can have quite a negative impact on economy.

 

2019 if I drive easy 30mpg on the back streets
If I’m on the highway I’m getting 26 or so start letting that boost kick it and It’s downhill from there

 

On the rural 55-MPH roads around here I can easily get MPGs of 35-37 or so if I am just driving normally - IE, no hard launches, racing, speeding etc. 2021 WRX 6-speed. Mileage drops a lot on the Interstate at 75 MPH.

 

I used to drive my subarus spirited when i'd go out til I bought something faster now its just the A to B. It never really wow'd in the MPG department but its not the worst. To go along with the ability to drive in any weather is a huge plus. I think on road trips I could get close to 330 miles on a tank which isnt bad. All and all I love it for a daily.

 

What the fuck? Do you all tow the car halfway? I get around 22-24 on slow rural roads, 19-20 hwy, 17-18 city & 14-15 on mountain roads.

 

Yours does seem particularly bad, but I suspect most people that drive their WRXs claiming to get in the 30+mpg realm are merely trusting the far-too-optimistic trip computer. It's already 2-3 MPG optimistic on my STI.

That's why I like Fuelly. They ask you to calculate your economy at the pump which equalizes a lot of things, but even then, Odometer error is an issue. I'm running 255/45/18 on my STI which means my mileage runs about 2.5% slow. My calculated economy will also differ by that amount.

 

I took a 3hr trip of mostly highway and interstate and got over 30mpg. In mixed driving, I see about 24mpg. I don't baby it either. But then again, I try to drive in such a manner where I can maintain speed in the corners so I'm not constantly accelerating.

 

Calculated at the pump or with the trip computer?

 

Nice.

Glad to see Subaru has been improving the economy in spite of the displacement increase which was a weird choice.

Do you have a 6MT or CVT?

 

It's not demarcated by 5 vs 6 speeds, but specifically the STI 6MT. That transmission is only found in the Impreza STI, Legacy Spec B and STI variants of Legacy and Forester overseas.

 

I will say I wanted to test it last night driving 50 miles to a hiking spot and it was getting roughly 30-32 MPG in cruisecontrol at 70 in a 22 wrx.

 

Yep...the only way you're going to get the EPA mileage estimate on the highway is if you're doing 90mph the entire time. If you do 70mph then you can get over 30 easily.

 

This thread makes me want a VA or VB WRX. I text people if mine cracks 20.

 

I contemplate selling the wrx on the daily. I already have a fun car in my 23 corvette (11MPG average) and I don't really need a daily that runs on premium but its excellent in winter and checks all the boxes. Plus interest rates are not coming down anytime soon. So maybe the cost of gas vs buying a new corolla or something is worth it.

 

I contemplate selling the wrx on the daily.

Yeah...on paper the WRX isn't spectacular. But there is something about driving it that puts a smile on my face.

 

people enjoy vehicles differently or buy them for different reasons. Theres some old guys who barely break 55 mph in Ferraris.

 

I hear ya JBRAVO,
Its like the old grey haired Callaway hat wearing geek driving his Z06 corvette 20 mph under the speed limit.

 

Somebody's gotta buy all those white New Balance sneakers and jean shorts...

 

Or the ford raptor crowd going slow over the railroad tracks ....lol

 

Saw your post yesterday and I wondered how accurate my MPG gauge was since the WRX only has 1100 miles right now. So I filled the tank today with the trip gauge showing 156 miles traveled at 27.2 mpg. The tank took exactly 5.7 gallons which is 27.3. I think these things are pretty idiosyncratic. I remember changing and oil pressure sender on my race car and in the exact same condition there was 5psi difference.

 

I'm happy my 2023 6 speed is between 27-29 mpg and isn't even broken in yet. My 23 Crosstrek 2.5 CVT only gets 2-5 mpg more. My only hesitation in getting a WRX was the 19/26 mpg rating, but I can't see how I can get that little. EPA ratings are usually high, especially since we only have 10% Ethanol near me.

 

I'm not certain of the testing methodology, but Subaru may indeed be a bit conservative with the new cars.

Real world (Fuelly)

 

I did a big road trip Saturday leaving the Nashville area and driving the back roads to North Carolina to drive Cherohala Skyway and Tail of the Dragon. Even doing LOTS of high speed driving on the interstate and driving the car hard in the twisties, my round trip milage was 27mpg....and that's with a tune running 17psi of boost.