Jaguar claims diesel technology has now reached a level where it is suitable for its cars, although both the company and its dealers have been keen to see the introduction of a diesel for years where it has lost out – particularly in Europe – to other premium cars with an array of diesel motors.
The 2.7 V6 engine is a product of the Ford-PSA diesel partnership and will see service in the Jaguar S-type and eventually the XJ, with other versions going into Peugeot, Citroen and Land Rover vehicles.
Anyone interested in seeing the engine in an X-type could be in for a long wait – Jaguar says it will fit, but has done no investigation into getting a V6 diesel X-type into production.
Using twin turbos, the 2.7-litre engine develops 206bhp and 320lb-ft of torque. Engineers claim it is up to seven decibels quieter than a comparable engine in a leading German rival, while it has been priced against the new BMW 525d – a car offering 177bhp and 295lb-ft – and sits £1,900 higher in the S-type range than the equivalent 201bhp 2.5-litre V6 petrol car.
The entry-level 2.7D comes with climate control, a CD player, electrically-adjustable front seats and 17-inch alloy wheels.
Paul Walker, the S-type's chief programme engineer, said the car had helped Jaguar double its sales worldwide since its launch in 1999, and despite only being available as a saloon and up to now with petrol engines, it accounted for 18% of the petrol executive car segment in Europe.
But petrol engines only account for 20% of the whole executive car sector in Europe, and Jaguar thinks the diesel engine will help the S-type take a significantly larger share of the market.
It should also help boost the S-type's presence in the corporate sector in the UK.
James Drake-Lee, corporate operations manager for Jaguar, said the fleet business was typically about 30% of S-type sales, but corporate sales should account for most diesel models sold.
There is a new six-speed manual offering Euro IV compliance and carbon dioxide emissions of 189g/km, while the six-speed automatic, still a Euro III compliant car, has CO2 emissions of 208g/km.
Drake-Lee said the fuel consumption and emissions penalty of making the automatic Euro IV compliant at launch would negate any benefit to the driver, so it will remain Euro III compliant until closer to the deadline in January 2006.
While the S-type still majors on appeal for older drivers – many who perhaps remember an original S-type in the family –it does seem there is more to attract those below the age of 50.
The X-type diesel has done much to bring in younger drivers to Jaguar, and those still choosing petrol models upgrading from volume upper-medium cars have tended to choose manual transmissions, while downsizers tend to go for automatics.
Unlike the X-type diesel, where there is currently just the five-speed manual transmission, drivers have the choice of a six-speed manual or a six-speed auto, but manual take-up is expected to be about 5%.
As well as the new diesel engine, the S-type has been freshened up following its minor facelift two years ago. There is a revised front end with a re-profiled grille and aluminium bonnet (for better weight distribution), while the rear light clusters have been redesigned and the boot is slightly higher giving the new S-type a more aggressive stance.
Inside, there are more modern-looking instruments and Sport models and the S-type R are offered with the option of aluminium trim – the first time an alternative to wood has been made available in the S-type. The car that harks back to the 1960s now purrs confidently into 21st century Europe.
Behind the wheel
IT is always a challenge for a manufacturer offering a diesel engine for the first time because it has to be as good as all the others around which have evolved with the latest technology over the years.
Unlike the X-type diesel which uses a modified version of the Ford Mondeo's 2.0 TDCi engine, the S-type is the first car to use the new six-cylinder engine developed jointly by Ford and PSA Peugeot-Citroen.
Twin turbos take the power output above 200bhp, although the recently announced Land Rover Discovery 3 will use a single turbo version and we can expect to see it in various guises within the Ford empire and Peugeot and Citroen models in the next few years.
The first test of a diesel engine it to switch on the ignition when the car is cold and listen. It might sound crass but in the S-type diesel there was a surreal moment when I thought I could have been sitting in a petrol version. The engine caught and settled into a muted purr with none of the characteristic diesel 'clatter'.
Either Jaguar had done an exceptional job on noise reduction and insulation or we had been conned into thinking we were in a diesel.
Opening the window removed all doubt as it sounded like a diesel from the outside. However, the confusion returns soon after moving off, as the power delivery is smooth and responsive. The engine is lively from below 1,500rpm and never seems to give up all the way to the rev limiter.
The manual transmission will have limited appeal, and in the left-hand drive models available needed a firm hand and a little patience to change up through the 'box – first to second feeling particularly belligerent.
The 2.7D with an automatic transmission felt far more at ease with itself and offered effortless performance. Power and torque might fall short of the new 3.0-litre Audi A6, the BMW 530d and the Mercedes E320 CDI, but acceleration it still surprisingly brisk and the Jaguar has the edge on all its rivals in terms of refinement.
The changes to the S-type styling means the car is now far more elegant, with some of the fussy detailing banished to history, but a few of the shortcomings still remain: rear-seat space falls short of expectations and the boot is still too shallow. Presumably these will be addressed by an all new model still a few years away.
JAGUAR'S S-type 2.7D redefines expectations of noise, refinement and power delivery for premium diesel cars. Finally the S-type can balance high-performance with low wholelife costs thanks to the new engine.
Model: S-type 2.7D
Engine (cc): 2,720
Max power (bhp/rpm): 206/4,000
Max torque (lb-rpm): 320/1,900
Max speed (mph man/auto): 143/141
0-60mph (sec): 8.1/8.2
Fuel consumption (mpg): 40.0/36.0
C02 emissions (g/km): 189/208
Fuel tank capacity (l/gal): 69.5/15
Transmission: 6sp man/6-sp auto
Service intervals (miles): 12,000
On sale: June
Prices (OTR): £27,670-£31,670