Subaru WRX vs Ascent - Octane vs Horsepower

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Roberts9156

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Mar 15, 2026
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Subaru WRX and Ascent have the same engines with little different tunes. The WRX has only +11 Horsepower and -19 ft-lbs torque while requiring premium gas.

This doesn’t feel like a great tradeoff at a dollar more per gallon for premium. What am I missing??
 
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I mean, I get the more power the better… Just seems like an awfully expensive (over the life of the vehicle) way to get only 11 HP. I would have thought Subaru could have pushed it harder on premium.
 
Roberts9156 said:
Subaru WRX and Ascent have the same engines with little different tunes. The WRX has only +11 Horsepower and -19 ft-lbs torque while requiring premium gas.

This doesn’t feel like a great tradeoff at a dollar more per gallon for premium. What am I missing??
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With an 11HP gain it sounds like all they did was change the octane recommendation and fudge the dyno numbers.
 
Roberts9156 said:
Subaru WRX and Ascent have the same engines with little different tunes. The WRX has only +11 Horsepower and -19 ft-lbs torque while requiring premium gas.

This doesn’t feel like a great tradeoff at a dollar more per gallon for premium. What am I missing??
Click to expand...
ECU is programmed differently I am sure. Drive them both it does not feel like 11hp more, feels like a bazillion more. That being said, there is a cobb kit for outback xp and ascent that bring you 40hp? on 93, and can take any gas higher than 87... 89, 91, up to 93. the limiting factor for it is the CVT transmission. New wrx sti has either manual or a performance transmission so the ecu is letting the engine go harder?... so I think its the computer holding back on the ascent and the outback xts. Someone chime in if Im way of here...
 
Take them both to the dyno and compare actual output on same & different fuels. You're not going to get this info from Subaru direct.
 
Arc said:
With an 11HP gain it sounds like all they did was change the octane recommendation and fudge the dyno numbers.
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I don't know if they fudged the numbers. WRX dyno sheets show it probably has 20hp over what the factory stated

The fa24 is very responsive to tuning could easily handle another 50hp from the factory while maintaining OEM reliability

My guess is they did that way for the same reason the WRX is sold with summer tires. To make the test numbers look as good as possible and to limit factory torque output with that transmission. And possibly...maybe...bc they had plans for an actual STI at one point so they needed to retain a stark power figure contrast between the STI and standard WRX
 
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otbflo said:
ECU is programmed differently I am sure. Drive them both it does not feel like 11hp more, feels like a bazillion more. That being said, there is a cobb kit for outback xp and ascent that bring you 40hp? on 93, and can take any gas higher than 87... 89, 91, up to 93. the limiting factor for it is the CVT transmission. New wrx sti has either manual or a performance transmission so the ecu is letting the engine go harder?... so I think its the computer holding back on the ascent and the outback xts. Someone chime in if Im way of here...
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The Ascent is heavier than the WRX. And I'll bet the Ascent has lazier transmission tuning and more of a throttle lag making it feel 100x slower. You don't want the soccer moms and grandmas chirping the tires when they leave the stoplight and the kids spilling their chocolate milk and Cherios everywhere!

I'd be willing to bet the WRX is tuned for more top end and Subaru is expecting them to be driven harder, thus the recommendation for Premium. They probably tune the Ascent to handle stop-and-go and speedbumps with more mid-band power.
 
otbflo said:
ECU is programmed differently I am sure. Drive them both it does not feel like 11hp more, feels like a bazillion more. That being said, there is a cobb kit for outback xp and ascent that bring you 40hp? on 93, and can take any gas higher than 87... 89, 91, up to 93. the limiting factor for it is the CVT transmission. New wrx sti has either manual or a performance transmission so the ecu is letting the engine go harder?... so I think its the computer holding back on the ascent and the outback xts. Someone chime in if Im way of here...
Click to expand...
I found the Ascent gets going well enough, but it has to be tuned more conservatively as someone will be towing a trailer up a very long pass, and to get better mileage on 87, and lots of people don't want to have an engine that revs to make power. To me it feels basically like a big V6, that has a very slight lag at low rpms if you like to move the pedal fast. Driven normally, it seems to make torque as fast as you move the pedal.

Also its very hard to figure out what exactly is going on with an engine/drivetrain with a CVT, a turbo with electronic wastegate, and electronic throttle body. The range of tuning options available to change how the car responds is huge. Even with identically tuned drivetrains, the WRX is 25% lighter, so it should feel quicker.

Even between my two simple subaru's(NA, CVT, electronic throttle), how they respond to a bit of throttle pedal is quite different. The Outback feels like it has much more power and is eager to gain speed, and the Impreza feels like its got a 2.0l NA in a 3100lb car...
It's just how they map the throttle plate to the pedal, and combined with how the CVT ratios change. Basically the Impreza kind of lives up to the laggy slow CVT stereotype unless you floor it, and the Outback was specifically tuned to not feel that way, and I'm sure lots of them never see more than 50% throttle pedal, as I think the throttle body is near WO.
 
So I wasn’t trying to compare the WRX to the Ascent in performance, just question the value making the WRX require premium gas. Not to be a bummer, but if you owned a WRX for 150,000 miles (@ 22 mpg and +$1/gal for premium), you spent ~$7,000 for a small amount more horsepower that only applies when flooring it across a limited RPM range.

I like the thoughts that maybe the WRX is under rated. I hope this is true.

Not that it directly relates anymore, but this article is interesting. https://carbuzz.com/features/jdm-gentlemans-agreement-japanese-cars-276-hp/
 
Roberts9156 said:
So I wasn’t trying to compare the WRX to the Ascent in performance, just question the value making the WRX require premium gas. Not to be a bummer, but if you owned a WRX for 150,000 miles (@ 22 mpg and +$1/gal for premium), you spent ~$7,000 for a small amount more horsepower that only applies when flooring it across a limited RPM range.

I like the thoughts that maybe the WRX is under rated. I hope this is true.

Not that it directly relates anymore, but this article is interesting. https://carbuzz.com/features/jdm-gentlemans-agreement-japanese-cars-276-hp/
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Even if peak Hp isn't that much greater, the wrx is probably tuned a lot "crisper" with higher boost at lower rpms, more advanced timing, leaner fuel mixture, and responds better at low and mid range rpm and throttles? It also can probably be run much harder before it gets into a situation where the engine needs to pull some timing, to control cylinder temps.
IMO Subaru was quite smart to keep the 2.4T on 87 for the non-sports cars.
I believe all the 2.4T have the same compression ratio, and AI tells me that the WRX manual says 87 is OK unless there is severe knocking.
I would kind of like a WRX but spending $1500+ extra on fuel per year isn't worth it for me anyways...
 
Roberts9156 said:
So I wasn’t trying to compare the WRX to the Ascent in performance, just question the value making the WRX require premium gas. Not to be a bummer, but if you owned a WRX for 150,000 miles (@ 22 mpg and +$1/gal for premium), you spent ~$7,000 for a small amount more horsepower that only applies when flooring it across a limited RPM range.

I like the thoughts that maybe the WRX is under rated. I hope this is true.

Not that it directly relates anymore, but this article is interesting. https://carbuzz.com/features/jdm-gentlemans-agreement-japanese-cars-276-hp/
Click to expand...

No no no. This isn't how car guy math works

An extra 11hp every day x 10 years and then carry the number of manual shifts you made all squared over turbo noises .... would be more appropriate measurement.

In all seriousness, I buy premium gas for most cars anyway. The 60 cents/gallon is worth it for me.

Or I use an ethanol blend which significantly reduces my cost at the pump while giving me the same mpg as regular gas.
 
IndyIan said:
Even if peak Hp isn't that much greater, the wrx is probably tuned a lot "crisper" with higher boost at lower rpms, more advanced timing, leaner fuel mixture, and responds better at low and mid range rpm and throttles? It also can probably be run much harder before it gets into a situation where the engine needs to pull some timing, to control cylinder temps.
IMO Subaru was quite smart to keep the 2.4T on 87 for the non-sports cars.
I believe all the 2.4T have the same compression ratio, and AI tells me that the WRX manual says 87 is OK unless there is severe knocking.
I would kind of like a WRX but spending $1500+ extra on fuel per year isn't worth it for me anyways...
Click to expand...
That's exactly what the manual says . A lot of guys run 87. I imagine 89 would be fine for most situations
 
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