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Subaru’s First Boxer Diesel Passenger Cars: Legacy Sports Tourer and Outback

Boxer Diesel Outback 2.0 TD.

Subarus’s first boxer diesel (earlier post) passenger cars—Legacy Sports Tourer and Outback—will go on sale in regions of Europe in February 2008.

The turbocharged 2.0-liter horizontally-opposed diesel engine develops 110 kW (148 hp) of power at 3,600 rpm and 350 Nm (258 lb-ft) of torque at 1,800 rpm, and is coupled with Subaru’s symmetrical all-wheel drive system. The Boxer Diesel meets Euro 4 emission standards with oxidation catalytic converters, a particulate filter and exhaust gas recirculation.

The most fuel efficient of the models, the Legacy Sports Tourer 2.0TD R, consumes 5.7 L/100km (41.3 mpg US) on the European combined cycle with 151 g/km of CO2. The Legacy Sports Tourer has a 126 mph top speed and 0-60 mph time of 8.5 seconds while the Outback (with fuel consumption of 5.8 L/100km, or 40.6 mpg US) is only slightly behind at 124 mph and 8.8 seconds for the 0-60 mph dash.

The new Boxer Diesel Legacy and Outback feature several unique features to suit their diesel application.

  • The engine has liquid mounts, with the body benefiting from extra sound-proofing to enhance refinement, while the five-speed manual gearbox has higher ratios to suit the diesel’s stronger torque and lower engine speed.

  • The power-steering is now electric to improve fuel economy and tuned for strong feel and response. Front spring rates have also been tuned to suit both the diesel engine and new steering system.

  • The Boxer Diesel’s front brakes have also been uprated and the gear-lever length reduced by 10 mm for a sportier, shorter throw.

  • The air-conditioning unit has been modified to provide hot air earlier in the engine’s warm-up cycle, diesel engines having different characteristics to gasoline powerplants.

The boxer turbo diesel. Click to enlarge.

Use of the horizontally-opposed boxer engine layout enabled the creation of a light, compact, strong unit with reduced vibration, noise and internal friction compared to an in-line engine and for an ultra-low center-of gravity. The entire engine and transmission are not only mounted very low down but also within the wheelbase, further boosting chassis dynamics.

The 2.0-liter Boxer Diesel has a class-leading light weight with the horizontally-opposed pistons effectively cancelling out the secondary harmonic vibration.

The crankshaft is short and highly rigid, minimizing the vibrational noise of many diesel engines. The superior balance of the horizontally-opposed engine means internal rotational inertia and friction are reduced compared with an in-line engine.

The engine has a ‘square’ bore and stroke of 86 mm and a compression ratio of 16.3:1. Compared to Subaru’s 2.0-liter gasoline engine fitted to the Impreza, Legacy and Forester, the 2.0-liter Boxer Diesel has a 11 mm longer stroke and 6 mm smaller bore for a capacity of 1,998 cc versus 1,994 cc.

Thanks to a bore pitch shortened from 113 mm to 98.4 mm, the overall engine block length is only 353.5 mm compared to the gasoline version’s already compact 414.8 mm.

The block is of a rigid semi-closed deck design, while all five main bearings in the alloy cylinder block use metal composite supports for added strength and durability. It also enhances refinement, providing a similar thermal expansion to that of the crankshaft.

Extra water-cooling slits have been added between the cylinder bores and the high-strength pistons are squirted with oil to enhance cooling. The large ends of the connecting rods feature an asymmetrical profile for assembly precision and reduced friction.

The high-strength crankshaft has a special surface treatment to withstand the diesel engine’s high combustion pressures while the uprated cylinder heads have roller rocker arms. In addition, the cam-drive is via a chain system that better handles the variations in torque of a diesel engine.

The new Boxer Diesel uses an advanced 180 MPa (1,800 bar) common-rail fuel-injection system. Special, short-length solenoid injectors ensure the engine’s width is no greater than that of the 2.0 litre boxer gasoline unit, despite the diesel’s longer piston stroke.

The variable nozzle turbocharger ensures the correct boost throughout the engine’s rev-range and its low center-of gravity position under the engine and close to the catalytic converters increases environmental performance.

The Boxer Diesel engine will initially only be fitted to European-market cars, with the yet-to-be introduced new Forester receiving the engine in September and new Impreza three months later.

On sale from February 2008, the Subaru Legacy Sports Tourer and Outback crossover mid-sized are priced from £19,995 (US$38,800) for the Legacy 2.0 TD R model.



Europe only right? If so, then I'd hope they carry over the electric power steering and work on a GDI 2.0L gasoline version if they don't plan to bring over the diesel.

The 2.5L is a strong motor but just not fuel efficent enough for me to purchase a subaru.


I like the boxer engine and the electric power steering. Subaru has a loyal customer base and has evolved through the years, I hope this car is a success for them.


I don't buy Subaru in the US because of poor gas mileage. If they bring the diesel in then I'd run down to the dealer for a test drive.


These can't come to the U.S. soon enough!

Current gasser Subies are stuck at 20 mpg city, and about 25 mpg highway - less if you choose the higher-performance turbo models that require premium.


I don't buy Subarus because I don't want people to think that I'm light in my loafers.


Subaru ( from Fuji Heavy Industries ship builders) seem to to be good at keeping it simple if at te expense of refinement, and dont get too stuck trying to do the same as competitors.
If the engine can be retrofitted on the same platform, or bolt up, then there will be room for upgrades, and long model runs I could overlook the fuel efficiency issues.
I know thats a lot to expect
Innovaters incl OE may provide addons as available.
They started cheap , but seem rather exe these days.
My issue with Subru run toward the design flaws remaining in your face for ever owing to long model runs, in the same way as the good points acheive a loyalty bonus.

Stick it

Ejj, punk-ass. My STI got me laid by the finest pieces of ass you could only see if you paid. Get back in yo minivan and go to shots night at Hooters, since yo house frau fat-ass wife don't give yo hairy chest the time of day no more. MUHAHAHA!


My memory is playing tricks on me again so perhaps someone can remind me. Is the Euro 4 emission standard a stricter or laxer emissions standard then the US Tier2/Bin5 reg? If it's a higher standard then why not intro in the states?
In any case I hope they do get them over here to the US soon. Two of my first three cars were Subaru and they ran just fine, good service and support from the dealers too.

Rafael Seidl

@ Larry -

T2B5 is about 6-7 times stricter than Euro 4.

Michael Chomiczewski

@ Larry - I doubt we'll be seeing these states' side because of emissions. Ppl often drool over how wonderful it is in Europe with all those efficient diesels but forget that most if not all diesels sold in Europe are simply to dirty to be sold in the US (and not just in the North East and California, either). Perhaps when Euro 5 kicks in...



The Outback is classified as a light truck in the US. Do they also have to meet T2B5? Subaru will have to introduce diesels soon. They don't really have a hybrid, PHEV, or PEV on the horizon. Diesels are the only way they (and most other automakers) can meet new CAFEs. Also, don't forget. The new CAFE #s are just temporary. When California is allowd to set their more strict requirements (and they will, probably in about 2 years) it will be the new standard.


P.S. I own an outback and the gas mileage is abyssmal...I wish I had never bought it. I will never own another one until it has respectable fuel economy.

Maple Leaf

In friendly, we are not the 51st state and trying to pretend we care about the environment Canada, 5.7l/100km would get you $1500 in your pocket.

Nice for a 260lb-ft 4x4 with a throaty flat-4 soundtrack.

Different worlds...


The regular outback gets mileage comparable to similar vehicles such as the Honda CRV, for those that really need AWD. Where Subaru could really improve is the smaller model, the outback sport, which gets only about 1 mpg better than the regular model, due to the 2.5 liter engine. One of the potential benefits of returning to a 55 mile per hour speed limit is that people would feel less need to buy overpowered cars.


I heard that the 55 mph speed limit was set that low, because they never intended to keep it that low for very long. Maybe 60 mph would be more practical for the long run and save fuel from the 70+ mph that people travel on freeways.

It seems to be a political hot button issue that is unpopular with driver/voters. Even if you could prove that a 60 mph speed limit could save the U.S. millions of barrels of oil per year, the will may not be there.

Top Gear

"Besides strong performance, the boxer diesel offers very good fuel economy, low carbon dioxide emissions, and low particulate emissions thanks to a filter, advanced exhaust catalyst and exhaust gas recirculation; with only a little tweaking, it will even be able to meet the ultra-stringent emissions regulations for sale in all 50 American states"


Subarus are loved and adored by dudes who play for the other team....


Arnold, the "long model runs" on Subaru's are five years. Every model sent to the US gets a complete redesign on a five year cycle. Generally there is a mid-cycle refresh every other year with a final facelift in the last year of the platform.

Contrast this with domestic producers (aside from their best-selling trucks) and it's a very short model run. Remarkable for such a small volume company, actually.

FHI's president at the 08 Detroit show said this engine would arrive in the US around the middle of 2010. That would roughly correspond to their release of the 2011 Forester, to go by history. (Impreza in the late winter, Forester in the late spring, Legacy & derivatives (outback, Baja) in the autumn). Tribeca hasn't been around long enough to have a pattern...)


55 is about what the EPA has identified as the speed that gets the best fuel economy for most vehicles. Some high geared V8's actually do better at 65, but these are dinosaurs that are already being phased out. Some small diesel vehicles do significantly better at speeds down to 35. There is very little diffence in fuel economy between 55 and 60, but implicit in any speed limit is the realization that people know they can drive five MPH faster without getting a ticket, and driving 65 results in approximately 10% worse fuel economy.
California actually had a soft 55 MPH speed limit through the 1950's. It was observed more then because we didn't have cars that could effortlessly go 80.


I think we could see within a year Subaru showing a US-legal version of its new boxer turbodiesel engine, probably with a little more power due to the use of even higher-pressure common-rail direct fuel injection (similar to what Honda did with the i-DTEC engine, which is rumored to be rated at over 160 bhp in US-legal form).


I'll wait until you guys start wrecking these cars, then I'll just do an engine swap of it into my impreza.

Todd Baker

To the people who said Subaru's only get 20 city and 25 highway is out to lunch. I have a 2007 Outback and on this last tank of mostly city driving I got 28MPG.

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