Care and feeding of a turbo car
March 10, 2014 8:20 AM   Subscribe

We're shopping for a gently-used Subaru Outback, and just spent the weekend looking at the 4-5 options that met our criteria within a 50-mile radius. The one that seemed to be in the best shape (not too many miles, not too old, one previous owner, well-treated, etc.) happens to be the turbo model. I've never owned a turbo car before; what are the pros and cons?

As a caveat, I'm not intrinsically a car enthusiast; I've never really considered wanting a turbo for the rush of power, the feelings of superiority as I zoom onto the highway, etc. I don't actively want a non-turbo either - I've just never considered it one way or the other. In the test drive, it was kind of cool, I guess, though there was too much traffic to play around with it much, especially with the dealership guys sitting in the back seat. :( (n.b. I don't need advice on used-car shopping, that's just the context)

Things I'm interested in: How does turbo affect the gas mileage? Does it mean I'd need to use premium fuel? Does a turbo need more maintenance or have more expensive parts than a non-turbo?

Basically, the immediate cost is that this fancy car (sunroof, leather, better stereo, etc, as well as turbo) is blue-booked at about $1000 higher than a comparable standard-edition model - but it is a nice car, and younger than most things on the market (standard-model subarus correspond with economy-minded drivers like myself, who wouldn't dream of selling a rugged car with under 90,000 miles on it) so we'd really consider getting it. But, I worry that this wouldn't be a great choice, if it'll end up costing us more down the road.

Bonus question: does having turbo change the driving style? If we get this car, what should I start doing differently to take advantage of it?
posted by aimedwander to Shopping (12 answers total)
My husband is one of those Subaru-obsessed guys, and here is what he has to say:

Subaru turbos do tend to require premium fuel, and they definitely require synthetic oil as well as more frequent oil changes. For gas mileage, with highway driving or low-acceleration driving, a turbo can actually improve mileage vs. a naturally-aspirated engine because turbos are just an inherently efficient design that utilize wasted energy. But they also let you burn more gas if you drive hard, which would obviously lower fuel mileage.
posted by something something at 8:31 AM on March 10, 2014

The obvious worry with a turbo Subaru, especially one that has fewer miles on it than you would expect, is that it has been rode hard and put away wet. Granted, a turbo Outback isn't a WRX -- a used WRX is well into the realm of "Not even with someone else's ten foot pole."

But whoever the original owner was looked at the standard model's already pretty healthy 175hp and said "Nope, need more." Presumably they did that for a reason, and I'd be wary of it for that reason.
posted by ROU_Xenophobe at 8:40 AM on March 10, 2014

ROU_Xenophobe: "But whoever the original owner was looked at the standard model's already pretty healthy 175hp and said "Nope, need more." Presumably they did that for a reason, and I'd be wary of it for that reason."

175hp is pretty gutless in a 3500 pound car, especially if you plan to tow anything. For that reason, I wouldn't expect that an Outback with a turbo has necessarily been beaten within an inch of its life any more than I would expect the average V6 RAV4 to have been driven hard.

I would stay away from a WRX unless I knew the owner. Or a Mazda "SPEED" line, or an Infiniti G series owned by anyone not at least 40 years old.
posted by wierdo at 9:10 AM on March 10, 2014 [2 favorites]

In terms of driving style, you'll become aware of turbo lag. The turbo works by extracting energy from the exhaust with a turbine to spin the compressor. Basically the engine runs, exhaust gas spins a turbine, turbine spins the compressor, compressor gives the engine more oxygen and thus boosts power. So that boost isn't quite instantaneous since it needs to get energy from the exhaust.
In practice you'll learn that if you want that power boost you'll need to plan on it. The first couple of times you're looking for that when you merge on the freeway it won't be there until you're closer to the merge, and then after some time your body learns to press the gas just a little earlier than your normally-aspirated engine does and you'll feel the acceleration at the right time.
posted by Runes at 9:14 AM on March 10, 2014

What a turbo does (practical, not technical) is make a smaller engine perform and deliver power like a bigger engine. This (physics is a bitch) puts more strain and wear on the (smaller) engine. It HAS to. That being said, the type of engine Subaru uses is very well suited to turbocharging and gets a HUGE benefit from it (more than an inline or V configuration would from the same size turbo). Subaru also has a very long and continuous history with turbos (longer than any other mainstream manufacturer I can think of) and they are very good at designing their engines for it and keeping the turbo size small and manageable (as long as you stay away from the WRX/STI boy racer models). A useful way to think of turbo is it has two different engine sizes-a small one when you are at lower rpm and less than wide open throttle (WOT). and then, when the turbo is in use, a big engine with lots of power and a thirsty appetite.

Turbos do usually require premium fuel to get the most out of the engine-including long engine life. The turbo 'crams in' more air and fuel into the engine and this effectively raises the compression of the engine and that requires a higher octane rating in the fuel to avoid knock-which is BAD for engines. Modern engine management systems can pretty effectively avoid this knock while using lower octane gas with some black magic(avoid long technical discussion-Google knock sensor if your curious). But this means the engine won't make the power you expect or get the fuel mileage it can.

You want to use synthetic oil and REALLY stick to the schedule maintenance interval-turbos generate a LOT of heat and that is rough on the oil. Synthetic handles it a LOT better.

If you drive in a 'spirited' manner the turbo engine is going to get a lot worse mileage-the only way to get more power is to burn more fuel, so if you drive the engine at max power it is going to burn more fuel. However, and this is the magic of turbocharging (or more technically correct-turbo super charging), if you drive in a controlled sedate manor the car is going to get the fuel mileage you would expect of a much smaller engine since you won't be using the turbo (much). But when you need it-high altitude hill climbs, towing, passing the slow truck, accelerating to 80 to match traffic on the interstate, you have a big engine and can zoom on in.
posted by bartonlong at 9:15 AM on March 10, 2014 [2 favorites]

There was a period of a year or two in the mid-2000s where turbo-model Subarus didn't last very long. A family member drives Subarus exclusively and really likes them, but when she got a new one from one of the problematic model years, the turbo burned out and she had to replace the entire engine on her Legacy after 60,000 miles. (She is not a hard driver by any means.)

Please check consumer reports' auto guide or website--you may have to subscribe, but the info is worth it. The year with the issues stood out like a sore thumb in their ratings.
posted by homodachi at 9:20 AM on March 10, 2014

But whoever the original owner was looked at the standard model's already pretty healthy 175hp and said "Nope, need more." Presumably they did that for a reason, and I'd be wary of it for that reason.

Ehhh, not necessarily. For us it was between the Outback turbo and the Audi A4 Avant. The regular Subaru was just too sluggish. In the end we went with the Audi. But we're very conservative drivers, almost comically so, and take excellent care of our vehicles, and you would have been fine buying a turbo off of us.
posted by HotToddy at 9:38 AM on March 10, 2014

And that turbo lag that Runes mentions is the reason I didn't want the Subaru. I want responsiveness as a safety feature. And in fact soon afterward I did manage to avoid getting T-boned in the Audi by leaping forward, which the Subaru wouldn't have been able to do in time.
posted by HotToddy at 9:42 AM on March 10, 2014

If you want to tow anything, check the manual. I don't know anything about the Subarus, but I know of a Saab turbo that was strictly "don't tow."
posted by SemiSalt at 9:49 AM on March 10, 2014

I am the original owner of a 2004 Forester XT Turbo. Subaru's are quirky cars, but their motors are pretty spectacular.

First, regarding lag: Subaru has the best turbo engineering in the business, IMO. Lag is almost non-existent. Seriously.

Second, there are a couple of drawbacks: You'll want to use synthetic oil and, yes, the turbos require premium gas. They'll actually run acceptably on mid-grade, but it's nowhere near optimal for the engine.

Can't recommend Subaru enough.
posted by Benny Andajetz at 10:04 AM on March 10, 2014

You might be able to mitigate the cost of premium gas by blending. My car wants 91 octane so I fill with 93 octane gas in about a 2:1 ratio with regular 87 to reach 91. It takes an extra minute but last I checked, this was even cheaper than buying mid-grade 89 octane. This obviously wouldn't work in places where 91 octane is the highest available (California I think).
posted by exogenous at 10:38 AM on March 10, 2014

All very useful information! Thanks to everybody.

My particular problem is, I think, solved. Turbo in general has its pros and cons, and I would, in general, consider it - a bit of extra care for a bit of extra power/fun is a reasonable tradeoff. However, we're probably not going to get this particular car, because of the known design flaw in the Subaru 2005 turbo.
posted by aimedwander at 11:11 AM on March 10, 2014

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