Having already earned its stripes in Legacy, Outback and Forester, Subaru’s widely-acclaimed 150 PS Boxer Diesel engine is now available in the stylish Impreza, offering the perfect complement to the model’s supreme five-door practicality. The sporty, yet sophisticated, Impreza 2.0D offers customers a unique take on the small family car, combining spacious, hatchback flexibility and diesel frugality with the superb, confidence-inspiring grip delivered by Subaru’s trademark Symmetrical All-Wheel drive system.
The newcomer clocks up a refreshing 47.9mpg on the combined cycle to give a potential range of 670 miles on a full tank. In true Impreza tradition it’s no slouch, capable of hustling from 0 to 62 mph in a distinctly crisp 9.0 seconds before hitting a top speed of 127 mph.
The Boxer engine layout – very much a Subaru speciality – comes with all the benefits typical of its kind. Its compact size means that it sits low-down in the chassis to give every Impreza an ultra-low centre of gravity for outstanding handling, great grip, reduced body roll and agile steering. The horizontally opposed cylinder layout ensures class-leading noise, vibration and harshness and a smooth response that should maintain Subaru’s established reputation as a manufacturer of engines that last for years.
But beyond its exceptional refinement this punchy turbodiesel offers excellent flexibility and good throttle response, delivering a massive 350 Nm (258 lb ft) of peak torque between 1800 and 2400 rpm. Ably assisted by the carefully selected ratios of the six-speed manual gearbox, effortless performance in everyday driving conditions comes as standard.
Teaming the front strut/rear multi-link chassis with the sure-footedness of Subaru’s permanent Symmetrical All-Wheel Drive makes for a winning combination. Backed up by Subaru’s Vehicle Dynamics Control stability system, it means owners can drive safely in the knowledge that their Impreza will instantly divert power from the wheels that slip to the wheels that grip – it providing the security and reassurance of active safety at all times, whatever the road conditions.
What makes the Impreza Boxer Diesel driving experience all the more satisfying is the host of luxuries that come as standard, such as climate control air conditioning, Xenon headlamps complete with pop-up washers, four power windows, 6CD autochanger, front foglamps, heated front seats and cruise control. The large door mirrors, which can be folded in at the touch of a button, are electrically heated and adjustable.
The Impreza 2.0D comes in a choice of two grades, RC and RX. The former comes with all the equipment described above yet is still priced at a competitive £20,000 on the road. Step up to the RX at £22,255 and gain keyless smart entry, an electric sunroof, rear privacy glass, full leather trim and electric adjustment of the driver’s seat.
Like its petrol-engined siblings, the diesel Impreza is an altogether more practical proposition than its predecessor, designed with the express aim of appealing to a wider audience. All models share the same spacious five-door body, wider than the previous Sport Wagon and with a 95mm longer wheelbase for a comfortable and accommodating interior. It’s also a lighter car with a lower drag co-efficient to aid fuel consumption and reduce emissions.
The Impreza’s styling is a subtle blend of elegance and assertiveness, with a sporty stance created by the wide track, broad shoulder lines, side sill spoilers and stylish side body creases. The distinctive ‘hawk-like’ headlamp surrounds, overt bonnet scoop and short rear overhang give it a distinct personality, while 17 inch alloy wheels are fitted as standard.
Beyond its stunning looks is a car that is easy to live with and easy to use. Wide-opening doors and excellent headroom ensure effortless access to the cabin, and once inside, the driver has the benefit of a reach and rake-adjustable steering wheel, plus a height-adjustable seat to create the ideal driving position.
The light and airy cabin provides great visibility, while the cargo area has been designed to make the most of all the available space – helped in no small part by the compact multi-link rear suspension. It delivers the flexibility to fold in a pushchair, swallow the contents of the weekly shop or load up the family’s luggage for that long trip away. An electronic one-touch tailgate release makes the process that little bit easier.
On those cold winter mornings the standard equipment windscreen wiper de-icers and heated front seats will rapidly get you underway in comfort.
In-car sounds are delivered by a 6CD autochanger/radio with full MP3 and WMA playback via a high fidelity 10-speaker set up. And for those who prefer to listen to their favourite sounds on their portable MP3 player, there’s a handy aux-in socket located in the centre storage box for playback through the car’s speakers.
The RX model has the convenience of keyless access which simply requires a smart key to be kept in a handbag or pocket and a button to be pressed on either of the front doors to gain access. Once behind the wheel, the engine is fired up using a push button on the instrument panel.
All models come with a Thatcham Category 1 alarm and immobiliser.
Other premium touches on both models include a gas strut-assisted bonnet, LED (light-emitting diode) tail lamps, metallic interior decoration and leather trimmed steering wheel, gearknob and handbrake lever. Design cues for the interior call upon the multi-million pound investments Subaru has made in improving interior quality, as seen first in the Subaru Tribeca.
Clear, highly legible main instruments are illuminated with ambient blue lighting for improved visibility and surrounded by chrome plated bezels. Switching on the ignition prompts the instrument needles to sweep satisfyingly around their dials before returning to their rest position.
Outside temperature, fuel consumption and a digital clock are displayed at the top of the centre panel which falls easily within the driver’s line of sight. Beneath it is the audio system with its ergonomically-designed buttons, backed up by steering wheel mounted controls.
Climate control air conditioning also comes as standard, with simple to use dial controls for fan speed, temperature selection and distribution.
All four doors have useful storage bins, large enough to hold a 720 ml drinks bottle, while the glovebox with its damped lid and LED lighting is able to swallow 12 CDs. On the centre console there’s a useful storage tray complete with blue illumination, two cupholders and a large storage box/centre armrest. The latter contains the audio aux-in socket plus a 12V electrical socket.
THE BOXER DIESEL ENGINE IN DETAIL
- Exceptionally compact, light and strong
- Low friction ‘Boxer’ balance cancels out vibration
- Flat four’s low centre-of-gravity boosts handling agility
- Punchy throttle response
- Common-rail fuel-injection for greater efficiency
- Compact injector design reduces engine width
- Variable geometry turbocharger mounted beneath engine for low centre-of-gravity
- Highly efficient, fast warm-up catalytic converter also mounted beneath engine
Subaru has over 40 years of experience with the horizontally-opposed ‘boxer’ engine layout – indeed Boxer petrol engines powered the company to three Drivers’ and three Manufacturers’ World Rally Championships – and, not surprisingly, that experience has been brought to bear in producing this first diesel unit.
This approach has allowed Subaru’s engineers to create a light, compact unit which provides all the strength necessary for the added stresses of diesel combustion, while reducing vibration, noise and internal friction compared to an in-line engine. There’s also the added advantage of a low centre-of gravity. A liquid-filled engine mounting system ensures even less vibration and better handling performance.
The flat-four layout with its horizontally-opposed pistons effectively cancels out the second harmonic vibration (vibration at double the frequency of the engine speed) which means there is no need for balancer shafts, which in turn drastically reduces inertia and friction. A lively throttle response and good fuel economy are the result. Furthermore, a compact crankshaft sandwiched by the highly rigid cylinder blocks helps minimise vibrational noise.
Compared to Subaru’s 2.0 litre petrol engine, the Boxer Diesel has an 11 mm longer stroke and 6 mm smaller bore for a capacity of 1,998 cc versus 1,994 cc. Cylinder bore spacing is also reduced in comparison – 98.4 mm, down from 113 mm – which means the engine block length is only 353.5 mm compared to the petrol engine’s already compact 414.8 mm.
The good rigidity has allowed the blocks to be constructed from aluminium alloy for reduced weight. The block design uses the semi-closed deck type that has proven its durability in the turbocharged petrol engine, while all five main bearings use metal composite supports for superior refinement thanks to their higher rigidity and thermal expansion properties similar to that of the crankshaft.
The 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 common-rail fuel-injection system with the fuel being pressurised at 180 MPa before being fed into the common rail. This maximises efficiency, both in terms of power, fuel consumption and emissions.
The variable nozzle turbocharger ensures the correct boost at all engine speeds and placing it beneath the engine contributes to the Impreza’s low centre of gravity, where it also connects directly to the catalytic converters, boosting environmental performance.
The Impreza Boxer Diesel meets Euro4 emission standards thanks to an oxidation catalytic converter, a particulate filter and exhaust gas recirculation.
Like the Forester Boxer Diesel, the Impreza boasts a new six-speed manual gearbox. The wide spread of ratios ensures excellent flexibility across all driving conditions, strong acceleration and relaxed, high-speed cruising. Even at 70 mph the engine is running at just 2100 rpm.
A cable-type gear change gives a consistent feel while isolating transmission and engine vibration.
Imprezas have always boasted outstanding chassis dynamics thanks to their sophisticated All-Wheel drive system, long travel four-wheel independent suspension and the low centre of gravity Boxer engines.
Driving enthusiasts will be pleased to learn that the latest generation continues that tradition with a completely new platform that features a 95 mm longer wheelbase, front and rear tracks widened by around 50 mm and a sophisticated multi-link, double wishbone rear suspension.
The new front MacPherson strut and anti-roll bar layout is based on that used by the highly-praised Legacy. Special bushes and attachment points reduce road shock, while the previous subframe has been substituted for a 20 kg lighter, yet equally rigid cross-member. The result is a high level of lateral rigidity, improving both steering response and cornering stability.
An economical electric power steering system has been selected for the Impreza Boxer Diesel, carefully tuned for strong feel and response which is further enhanced by the more rigid mounting common to all of the latest Imprezas.
The compact multi-link, double wishbone rear suspension replaces the previous struts, freeing up valuable luggage space. Furthermore, because it is attached to a sub-frame via bushes, with the mounting section moved under the floor, road noise is reduced. Ride comfort is helped by mounting the springs and shock absorbers behind the rear wheel centre-line – with the wheel stroke itself moving rearwards.
Naturally, shock absorbers, spring rates and anti-roll bar settings have all been finely tuned to the characteristics of the new diesel-engined models.
The result is a supple, composed ride with precise geometry control for accurate straight-line running over uneven road surfaces, backed up by extremely responsive steering and handling.
Stylish 17 inch alloy wheels on both RC and RX models are shod with 205/50 tyres.
Unlike its competitors, the Impreza boasts permanent Symmetrical All-Wheel Drive as standard, so owners have the security and reassurance of active safety at all times.
Front to rear torque split in the full-time system is nominally 50:50, but the centre viscous-coupling senses which axle has the best grip and varies this ratio instantaneously according to the road conditions.
The security provided by All-Wheel drive is backed up by Subaru’s electronic stability system, Vehicle Dynamics Control. Using sophisticated sensors to detect side to side and front to rear slip, plus sudden steering movements, VDC controls oversteer and understeer and potential loss of control by braking individual wheels and regulating engine power in milliseconds.
The Impreza Boxer Diesel’s raft of safety measures are aimed at achieving the highest standards of both occupant and pedestrian protection.
Curtain and side airbags as well as driver and passenger front airbags are part of the standard specification, as are front seatbelt pre-tensioners.
Brake and clutch pedals are designed to snap away under severe impact, protecting the driver’s lower limbs. Two ISOFIX-compatible child seat mountings are provided on the rear seats complete with top tether anchors.
Impreza’s active safety package includes 4-channel anti-lock brakes (ABS) with electronic brakeforce distribution (EBD) and brake assist, with discs all round, ventilated at the front.
On the outside, the risk of pedestrian injury is reduced thanks to a more rounded contour to the top of the front bumper, a gently curved bonnet with increased space beneath and windscreen wipers which collapse, softening any impact.
High tensile steel of varying thickness is used extensively throughout the body, providing good crushability where needed while protecting the passenger area. The engine and transmission are designed to drop down beneath the floor thereby minimising cabin intrusion in the event of a severe front-end impact.
Key features that take the Impreza to new levels of impact safety include enhanced rear absorption characteristics and a rear frame height that’s been optimised for the average height of the frontal crush structure of other vehicles, more effectively dispersing energy throughout the body. The side frame is designed to ensure both front and rear doors can be opened after a collision, while the door handle and latch are connected with a cable to retain their functionality.
All Imprezas marketed by Subaru (UK) Limited come with the reassurance of a three year or 60,000 mile warranty plus 12 year anti-corrosion cover and three year paintwork warranty, backed up by a network of experienced, down to earth and approachable dealers.
This is in addition to three years’ membership of Subaru Assistance – a comprehensive home and roadside repair and recovery package throughout the UK and Europe administered by Mondial Assistance.
Like Impreza 2.0 petrol models, service intervals for the Boxer Diesel are 12,000 miles. Insurance group ratings for both diesel models are a competitive 11E (24E for the RC and 25E for the RX on the new 1-50 scale).
2.0D RC: £20,000
2.0D RX: £22,255