Category: Large Family 
Price Range: £20,400 to £27,400
Strong, smooth performance; refinement; a unique proposition; the usual Legacy strengths.
A little noisy at start-up; too idiosyncratic?
The most petrol-like diesel we've yet driven.
Subaru's much-underrated Legacy range has, until now, lacked one thing important to buyers of large cars this size: a diesel engine. But rather than simply buy an off-the-shelf unit from another manufacturer, the small Japanese company has now developed its very own diesel from scratch, to its own near-unique formula.
Like the petrol engines offered in the Subaru line-up, this new four-cylinder 2.0-litre, 150bhp diesel engine has a 'boxer' cylinder layout, also known as a horizontally-opposed design. The cylinders sit in two banks either side of the crankshaft, parallel to the ground, rather than in an 'in-line' (or V-formation) layout.
Subaru says that its boxer diesel is the first such engine in a passenger car and that it shares no components with the 2.0-, 2.5- and 3.0-litre petrol engines also used in the Legacy and Outback. It is compact, relatively lightweight, and the nature of the design gives an intrinsically rigid, strong structure; vibration and noise levels are low, and no balancer shafts are needed, thus saving further weight. Its shape - it looks upright and shorter front-to-back than conventional diesel engines - allows it to be easily positioned in the engine-bay for good front-rear weight distribution, mounted relatively low down to lower its centre of gravity.
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.
The engine is offered in the Legacy saloon, the Sports Tourer estate and the higher-riding Outback. It comes with a five-speed manual gearbox (an automatic will follow at a later date, though probably not within this generation of models) and, of course, Subaru's standard full-time four-wheel-drive system, which uses a central differential with viscous coupling. UK sales start in February 2008, and this engine will also appear in the Forester and Impreza ranges later this year.
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