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Discussion Starter #1
This might be a ridiculous question, but I was reading on the Suby website that when you are running on the space saver spare, you move or pull a fuse to change the car to 2-wheel drive mode.

I was wondering if I wanted to improve mileage in conditions that 4WD isn't very helpful, could I drive around well in this 2WD mode?
 

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That did apply to the older subarus , but I do not believe it will work on any generation 4 Outbacks .
 

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It will not improve fuel consumption.

All of the drive train (rear drive shaft, rear differential, axles, etc) are still on the car so there's no weight advantage. Your still moving the same car, with the same weight, and the same friction in rotating components. The only difference is that the front wheels are doing all the "pulling".
 

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I simply cannot abide useless people.
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That did apply to the older subarus , but I do not believe it will work on any generation 4 Outbacks .
This is correct. The Gen 4 no longer has this option.

And it won't help MPG because all the heavy parts are still there, whether or not they're getting power. And it was meant to be a "limp it to a mechanic" measure and not a regular setting anyways.
 

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Discussion Starter #5
I thought perhaps the lessened friction would improve mileage. Isn't that the reason many other AWDs like Honda CRV default pretty much to FWD most of the time?
 

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Discussion Starter #7
I knew I was probably going out on a limb with this one. Thanks for the explanations.

I bought my Outback for its quality and functionality as a crossover vehicle, and it appeared to present an overall package of greater value than the competition. 4WD was way down the list, and the claimed mileage seemed like not too much penalty was being paid for the 4WD - as with the Forester.
 

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I thought perhaps the lessened friction would improve mileage. Isn't that the reason many other AWDs like Honda CRV default pretty much to FWD most of the time?
All the same spinny bits are still spinning, that's the long and the short of it.

I think most other part-time systems are part-time because the AWD components are minimally sized to just 'help-out' on an occasional basis.

That minimal sizing does help keep the weight and the rotational mass down, but negatively affects durability.
 

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I always thought it was odd that it didn't come with a full-size spare.

Is there something built-in to the Gen4 OB to protect it from damage when being using a smaller spare?

I realize it's only supposed to take you to the nearest repair place, but what if the closest place is 20 miles away?

I know my Jeep which had Quadra-Drive it was a big no-no to use a smaller spare for even just one mile. My jeep came from the factory with a full-size spare and matching rim.
 

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Discussion Starter #10
Thanks CYN_Dave !

adgjqetuo - Good question on that space saver spare. Was curious myself.
 

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I always thought it was odd that it didn't come with a full-size spare.

Is there something built-in to the Gen4 OB to protect it from damage when being using a smaller spare?

I realize it's only supposed to take you to the nearest repair place, but what if the closest place is 20 miles away?

I know my Jeep which had Quadra-Drive it was a big no-no to use a smaller spare for even just one mile. My jeep came from the factory with a full-size spare and matching rim.
I've never found anything anywhere that actually stated it one way or the other, but the implication is that the AWD system will tolerate short, low-speed trips with one wheel wildly mismatched. Subaru has used more than one AWD system over the years, and some have restrictions that others don't. Distance, weight & speed limit are the main factors.

It is important to realize that operating with a temp spare is likely putting a lot of stress on the AWD, but not so much that Subaru won't maintain your warranty given an average number of flat tires during the span of the warranty.

It's not an area where you'd want to push your luck though. I recall that my car lists a 50 mile maximum, but yours has a different system. Read the manual that came with your car.
 

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^ I don't recall seeing a maximum recommended distance in the Gen4 manual (obviously the shorter, the better), but it is clearly stated that the spare should only be used as a replacement for the rear wheels - NOT the front wheels.
 

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Yeah - I read that too. Makes it a real PITA if you get a front flat.
 

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I thought perhaps the lessened friction would improve mileage. Isn't that the reason many other AWDs like Honda CRV default pretty much to FWD most of the time?
No. They are FWD most of the time because their AWD mechanism is a simple fully-on or fully-off function. When it's on there will be torque bind symptoms when tight cornering. Consequently, they opt for it being off most of the time, and kicking in only when a wheel loses traction (or the driver uses the AWD manual switch that is available on most of these vehicles). Also, on some of these makes, the AWD does not work above 40 mph, essentially, for the same reason.

With the Subaru, the AWD is always on with the degree of AWD engagement variable (computer controlled) depending on need (speed, gear, throttle position, engine torque etc). The control system works to no only deal with wheel spin, but it also functions "in advance" to prevent wheel slippage, for example, when accelerating rapidly.

The "part-time" AWD used by the others is a far simpler system that's less expensive and less complex both mechanically and in regard to the control system.
 

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I always thought it was odd that it didn't come with a full-size spare.

Is there something built-in to the Gen4 OB to protect it from damage when being using a smaller spare?

I realize it's only supposed to take you to the nearest repair place, but what if the closest place is 20 miles away?

I know my Jeep which had Quadra-Drive it was a big no-no to use a smaller spare for even just one mile. My jeep came from the factory with a full-size spare and matching rim.

Has more to do with the normal use of the vehicle - and cost vs weight savings etc. The limper spare works fine for 99.5% of all the owners so makes no sense for Subaru to add weight and cost to the car for a full size spare to make the .05% of the owners happy. Those folks tend to add many other things to their cars including being fine with hauling a full size spare in any manner of ways.
 

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Has more to do with the normal use of the vehicle - and cost vs weight savings etc. The limper spare works fine for 99.5% of all the owners so makes no sense for Subaru to add weight and cost to the car for a full size spare to make the .05% of the owners happy. Those folks tend to add many other things to their cars including being fine with hauling a full size spare in any manner of ways.
I've been considering getting a full size spare and doing 5 tire rotations. Maybe next time I need tires I'll do that, but that will be a long time away.
 

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Where would you put it?
 

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Some folks have found a little gentle persuasion will expand the wheel well enough to fit a full size tire.

Others always have an inflator in the car and stuff an uninflated tire/wheel in the spare space.

others haven't found out yet a full-size won't fit...
 
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