[dnagir]

Hi,

After some time off test driving different cars and considerations I finally settled on the Impreza which I should pick up end of the week.

But I'm still wondering why the S model had higher fuel consumption (in the specs)?

It's exactly the same engine. So the only thing I can thing of its the width of the tyres that would add some rolling resistance.

But the difference seems quite big for that.


Any reasonable knowledge on that?


Thanks.

 

[SoCal355]

I have a premium model and not so good mileage

Couple mpgs either way is nothing to worry about

 

[Linas80]

My Limited Trim is nearing the completion of the break in period (1000 miles). The mileage is about 24 mpg and at least 600 miles were on the highway.

 

[whichchris]

Should be because of the Active Torque Vectoring

 

[dnagir]

How does active torque vectoring affect fuel consumption on a freeway?

 

[ILuvMySubaru2]

That's what I call a straightaway question! :wink2:

 

[impreza-gang]

Probably the 18 inch wheels. It has the exact same engine as the rest of the models and no more horsepower than the rest. They are all the same speed. Bigger wheels = more road contact.

 

[ImprezaSport21]

It's the rolling resistance of the 18" tires, which are wider and softer, combined with more air drag for the same, and now throw in the greater rotational mass.

 

[Kevdog]

its the wheel size.

 

[Chitownpete]

Heavier wheels and tires hurt city mileage, wider tires hurt highway mileage. Many people are surprised when they upsize wheels and tires that their car is slower

 

[Jeffrey1087]

Agree tires are a factor and its the heaviest model of all trim packages. I have the sport and still get good mileage though. Avg 28.6 and im happy with that.

 

[xmconi]

It could be that the Sport models all come standard as manual. I don't know about weight for sure, but i really doubt that wheels are gonna make that much difference. I added a screenshot of the difference, I could have sworn it was worse on Subaru's website at some point.

 

[Slicktop]

Aren't the steel wheels of the base (most efficient) heaviest of all?


The Sport and other trims have 150lbs or so more curb weight, probably from the addition of features like a sun roof, more sound deadening, acoustic windshield...


Final drive might be a little "taller" as well, more effort required to get up to speed.

 

[jonscott25]

Get's better after break-in, with higher mileage.
2018 Sport, 12,800 miles
I usually get better mileage commuting, between 33 and 36 mpg weekly average.
Last fill up yesterday morning, 390.9 mi/11.67 gal=33.49 mpg.
[This includes legal passing, inspired cornering and playing around turns]

You should get even better mileage if you have a CVT.

previous post:

I drive a mix of city, back roads and highway.
2018 Impreza Sport hatch 5sp, now has 8K miles.

Fill gas tank specs
for the last 6 weeks:
8/7 = 35.75 mpg
8/1 = 34.02 mpg
7/26=32.32 mpg
7/20=34.19 mpg
7/16=32.50 mpg
7/11=33.35 mpg
Note: average mileage includes using AC this summer

 

[C J]

How does active torque vectoring affect fuel consumption on a freeway?

Because it uses brake pressure to help the car corner.

 

[BruceP]

I was going to suggest that the roof-rack will also reduce MPG.... but that is only a factor on the "Limited" models.

Perhaps the "ground effects" package (although it APPEARS more aerodynamic between the front/rear wheels) is also impacting MPG.

As far as wheel-weight is concerned, in the drag-racing world, every pound shed from a spinning wheel is equivalent to about 8 lbs of static weight. This is due to centripetal forces on a spinning mass. (spinning a bicycle wheel takes MUCH less force than equivalant-diameter car wheel) This is why the front wheels of a drag-race car are VERY skinny and light.

 

[C J]

I was going to suggest that the roof-rack will also reduce MPG.... but that is only a factor on the "Limited" models.

I think that was tested on Myth Busters and found to be false.

As far as the larger rims and tires adding rolling resistance and weight that is a given, but they look better and help the car handle better and that is all I care about.

 

[Zeroptzero]

As you move weight further away from the centre of the axles you require more energy/power to move them. Even if the weight of the wheels are the same or less, larger wheels sap power.

Right now on my weekly 4 hour highway drive I am getting 34 mpg's (US) ( 6.8 L/100 kms metric). 2020 Impreza Sport Tech. This is at 70 mph, cold winter temps (-5 degs C) and running crappy winter blend fuel (known to kill fuel economy). This is the exact same fuel economy I get with my 2019 WRX Sport on the exact same trip and same conditions. It is a bit better than my 2017 Honda HR-V with its 1.8L motor and AWD.

I'd like to see my Impreza improve a bit more, just passed 1000 miles break-in. I am just comparing it to my WRX, but my WRX gets phenomenal fuel economy, better than expected. Glad that my Impreza beats my Honda HR-V so that is good, and it drives a million times better.

 

[peaty]

When I saw the title the first thing that came to mind was the wheel weight.

Math warning > This is a cool excel sheet regarding wheel weight you can DL from my google drive here >Click Me<

Fun to mess with if you are curious.

Screenshot: