Seamless diesel for Jag XF

The Jaguar XF has been the success story of the year for the prestige importer in Australia. 511 units have been sold locally since the car's launch last year and those sales have buoyed the local distribution arm through what has been a very difficult period for the automotive industry in Australia.

Now, Jaguar has honed the XF (more here), adding a new flagship -- the XFR -- to replace the supercharged 4.2-litre XF that previously topped the range. The 4.2-litre naturally-aspirated engine is superseded by a direct-injection V8 displacing 5.0 litres and this powerplant is the basis for the new supercharged engine in the XFR as well. At the entry level, the 3.0-litre petrol V6 continues to hold the fort, but the ground-breaking new variant in the XF range is powered by a 3.0-litre turbodiesel V6.

Replacing the 2.7-litre engine fitted previously, the new oiler sounds like a petrol V6 and drives like a petrol V8, until about 4500rpm, at which point the upgraded ZF six-speed will find a new gear. We've driven the new models -- watch out for our review -- and the diesel is going to provide its German competitors with some pause for thought.

Developing 202kW of power and enough torque (600Nm) to make most people sit up and take notice, the diesel XF is 33 per cent more powerful than the smaller 2.7-litre V6 it replaces, but is also 10 per cent more economical (6.8L/100km in combined-cycle testing) and emits 10 per cent fewer CO2 emissions -- 179g/km. The secret lies in the unconventional sequential twin-turbo set-up, in which a large turbine provides boost at lower revs and the smaller turbine keeps the boost coming at higher revs.

Out here for the launch of the upgraded XF, Jaguar's Chief Program Engineer for XF, Kevin Stride, described the new powerplant development as "an evolution of the [2.7-litre] engine, but with a quite radical redesign of the controls and induction system".

"The first part of that is we have used what we would call a 'parallel-sequential turbocharging system," he said.

The upshot of that is "no lag, lots of torque straight away, as soon as you ask for it".

Out of respect for the new diesel V6, Jaguar has raised the price to position the diesel XF above the 3.0-litre petrol V6 which is now the sole entry-level variant in the range. Prices are now $109,450* for the XF with petrol V6 (up slightly from the '09 model year variant's $108,350) and the diesel has jumped nearly $8000 to $116,250*, but the extra bucks are worth it! The XF with naturally-aspirated V8 is priced at $147,900* and dealers will ask $208,450* for the XFR.

Those dealers will begin offering drives in demonstrators during July and customers will start taking delivery of the upgraded models in August.

With the exception of the unchanged petrol V6, all XF engines for 2010 run harder and cleaner than the smaller-displacement engines that preceded them. Both the atmo and forced-induction V8s now displace 5.0 litres, versus 4.2 previously, but the larger capacity isn't the end of it for the bent eights.

Employing direct-injection, the all-alloy DOHC engines develop in 283kW/515Nm for the naturally aspirated V8 and 375kW/625Nm for the supercharged engine in the XFR. Fuel consumption and CO2 emissions figures are 11.1L/100km and 264g/km for the naturally-aspirated engine, 12.5L/100km and 292g/km for the supercharged engine.

For the XFR -- which Jaguar claims will reach 100km/h from a standing start in 4.9 seconds -- the manufacturer has specified a new Active Different Control system and Adaptive Dynamics. The former relies on an electric motor to clamp the clutches, finding a middle of the road solution to the respective compromises of mechanical limited-slip differentials and conventional electronically-controlled systems. According to Jaguar, there's none of the low-speed understeer with this system, such as might be encountered in cars fitted with purely mechanical systems.

Adaptive Dynamics monitors and adjusts suspension damping to suit the prevailing road conditions. Jaguar chassis engineers have configured the system to monitor road-induced body motion 100 times a second and wheel position 500 times a second. Also taking into account steering input, the system can modulate damping force to optimise roll and pitch.

The XFR diverges from the lower-grade models in offering a faster steering ratio and larger brakes to haul it back down (potentially) from the electronically-limited top speed of 250km/h. It can be distinguished from the other XF variants by: unique 'Nevis' 20-inch alloy wheels; revised bumpers and lower front air intakes; sill extensions; bonnet louvres and grilles; four tailpipes and a boot-lid spoiler. Exterior colours available for the flagship are: Ultimate Black, Indigo, Liquid Silver, Lunar Grey, Porcelain, Botanical Green, Kyanite Blue and Salsa.

All XF variants feature a stiffer body, upgraded brakes, a four-point mounting for the differential (in lieu of a three-point mounting previously) and an improved ZF six-speed automatic for the new model year.

* Recommended price before statutory and delivery charges.

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