RENOWNED worldwide for its four-square “boxer” petrol engines, Subaru has now put its experience to good use in creating the world’s first boxer diesel-engined passenger car.

Compared to Subaru’s 2.0 litre engine fitted to the Impreza, Legacy and Forester, the 2.0 litre boxer diesel has an 11mm longer stroke and 6mm smaller bore for a capacity of 1,998cc versus 1,994cc.

First to get the 150bhp two-litre oil-burning implant is the Legacy Sports Tourer, which importantly returns a very commendable 49.6mpg on the combined cycle with emissions kept in check at 151 g/km.

It also has a 126mph top speed and a zero to 60mph time of 8.5 seconds.

As has been demonstrated over the years with the petrol engine, the square positioning of the cylinder positions makes for a more refined and quieter operation than conventional units.

Subaru also fits liquid mounts for the engine, 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.

Refinement is therefore a boxer diesel strongpoint and it is hard to really tell that you are behind the wheel of a diesel such is the whisper from the engine and the exhaust and typical diesel rattle is all but eliminated.

In these times of economic restraint the diesel option would therefore appear to be the best bet for the Legacy Tourer, which suffers little from the usual diesel complaints.

To cope with the additional weight of the diesel engine, the front spring rates have been tuned, which doesn’t make the Legacy too front heavy as can happen.

Getting it around corners is helped by the power-steering which is now electric to improve fuel economy and carefully tuned for strong feel and response while the brakes have also been uprated to brings things under control in double quick time.

Standard fitments also feature Subaru Vehicle Dynamics Control and symmetrical all-wheel drive.

Visual changes to identify the Legacy diesel include new cloth seat trim and a discreet bonnet air intake scoop.

These enhance the previous changes to the Legacy, which include a chrome wing-like motif for the grille, while the front wings have been restyled and feature a a crease-line which flows from the top of the “hawk-eye” HID headlamps.

At the rear, the Legacy Sports Tourer has three-dimensional rear lamps with a chrome strip linking each lamp to give an impression of width.

The latest Legacy interior features aluminium-effect strips running the full width of the fascia, flowing out “wing-like” from the centre panel. This accentuates the width but also cocoons the driver.

Soft-touch trim is extensively used and standard features include electrically adjustable driver seat with two-set memory function.

The new models have new cloth trim for the R versions while the RE and REn feature leather as standard.

Specification includes dual-zone air conditioning; cruise control; front, side and curtain airbags; a leather steering wheel; electrically-folding door mirrors; and a CD player with MP3 facility.

The new diesel range starts at £19,995 for the Legacy 2.0D R manual Sports Tourer.