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New engines broaden XF appeal

2009-06-04 10:18
Vehicle Specs
Manufacturer Jaguar
Model XF
Engine 3l V6, diesel, 5l V8
Power 175kW @ 6 800-, 177kW (202kW) @ 4 000-, 283kW @ 6 500r/min
Torque 293Nm @ 4 100-, 500Nm (600Nm) @ 2 000-, 515Nm @ 3 500r/min
Transmission Six-speed auto
Zero To Hundred 8.3-, 7.1-, 6.4-, 5.7 seconds
Top Speed 237km/h, 240km/h, 250km/h
Fuel Tank 70l
Fuel Consumption 10.5-, 6.8-, 11.1l/100km
Weight 1 690-, 1 820-, 1 780kg
Boot Size 500l

Lance Branquinho

Despite the brand’s cachet, Jaguar does not produce many cars, quite a few less than Porsche, in fact. Last year, only 65 000 units were dispatched from the Coventry facility.

Although now owned by Indian conglomerate Tata, Jaguar remains one of world’s most revered manufacturers.

Image though, has been a contentious issue, especially since 10 Downing Street usually has a Jaguar parked outside. The brand’s image has suffered from a debilitating Tweed and grammar school stereotype, which at times had little to with the actual dynamics of the cars on offer.

After Tata extracted Jaguar from Ford’s premium brand portfolio last year, Coventry finally had financial stability to do the Jaguar name justice in terms of thoroughbred engineering.

Contemporary Jaguar is now back in the business of making swift, stylish cars - instead of trading vintage slipper-and-tweed image appeal for a narrow, aristocratic, revenue stream.

Launched last year, XF heralded the rejuvenation of Jaguar as a brand, encapsulating the company’s ethos of building ‘beautiful, fast cars,’ to quote chief designer, Ian Callum.

XF design brings Coupe grace to the executive saloon market. Surface proportions and detailing blend sensationally. Makes an E-Class, A6 or 5 Series appear to be the work of a pre-school drawing class.

Effortlessly the most striking car on sale in the extraordinarily image conscious luxury saloon segment, XF’s engine line-up has now been thoroughly updated. In fact, this could be the most radical engine line-up running change in history for a sedan range not even two years old.

I can only conjecture the new engines were at the peak of their development cycle when Ford announced it was going to sell Jaguar two years ago. One suspects the new V8 and turbodiesel gems were kept back for deployment under the commitment of new ownership.

Whatever the rationale, this new engine line-up is resolutely high-tech and offers a thoroughly convincing blend of performance, whilst simultaneously reducing the XF’s environmental footprint.

Beastly V8s

For a significant epoch of its illustrious history, V8 engines were the antithesis of Jaguar’s design philosophy. Today, they are the company’s mainstay power units.

Mirroring the running changes to the XK range, XF’s V8s have increased in capacity from 4.2l by 800cc, to now displace 5l. Two derivates are available, either naturally aspirated or supercharged, with both benefiting from an astonishing array of mechanical engineering details.

Whatever Jaguar’s engineering corps might lacks in numbers, it sure makes up with dedication and ingenuity.

The newfangled AJ V8 GEN III engines are fuelled by direct-injection, delivered at 150bar via centrally located multiple outlet injectors, which ensure optimal air-fuel mixing and lower charge temperatures. These lower charge temperatures have in turn enabled Jaguar to raise compression ratios, on both supercharged and naturally aspirated engines, to 9.0:1 and 11.5:1 respectively.

Aluminium cylinder heads house a delicately balanced variable camshaft timing system, allowing 62-degrees of inlet and 50-degrees of outlet camshaft adjustment in operation on each of the four individual cams.

This generous camshaft adjustment range is actuated by valve action torque (the motion of valves opening and closing), instead of oil pressure, which has allowed Jaguar to employ a far smaller oil pump on the 5l V8, residing inside the engine architecture. Subsequently the new engine is 24mm shorter than its 4.2l predecessor.

Augmenting the generous camshaft adjustment range is a variable geometry intake manifold (VIM). Varying the length of its eight inlet tracts to effect differentiating power and torque characteristics on demand, the VIM system employs vacuum operated valves to shorten or extend inlet tract length.

Able to retract from 680mm at low engine speeds, to a more truncated 350mm as the V8 spins past 4 700r/min, the shorter flow path at higher engine speeds carries the benefit of greater airflow volume, optimising power and efficiency.

The result of all Jaguar’s mechanical engineering trickery is the V8 being a quarter more powerful in naturally aspirated trim than its predecessor. The XFR’s Eaton supercharged version outperforms the blown 4.2l V8 by 23%.

If you wish to tabulate it by numbers, the new V8 outguns its 4.2l forebear by 64kW, with the supercharged eight besting the old blown version by 69kW.

Befitting XF’s nature as a swift executive saloon, a flood of rotational force at low engine speeds was prioritised in the design brief.  With the unblown V8 delivering 515Nm at only 3 500r/min, and  XFR spinning 625Nm at an enviably low 2 500r/min, the Jaguar engine development team should be well pleased with themselves.

Stonking new 600Nm diesel

Although compression ignition premium saloons make an awful lot of sense in Europe, where subsidised high-quality diesel and prohibitive emission taxes factor heavily in purchasing rational, the local appeal is somewhat tempered.

Severe local operating conditions, appalling diesel fuel quality combined with scant environmental concern when purchasing motorisation, makes the appeal of a diesel XF nearly unfathomable for me.

Honestly, is your typical XF customer really bothered by fuel costs?

The compression ignition XF’s miserly consumption characteristics are of little consequence other than perhaps extending range, which, in the Cape Town to Jozi trans-Karoo scheme of things makes some sense if you want to test bladder endurance…

Combining a sequential parallel twin-turbo within the V6 configuration generates epic rotational force figures with virtually no turbo lag from the new 3l turbodiesel. Service intervals are very optimistic, at 26 000km between visits.

What if the new diesel XF was dynamically validated?

Suppose it was stupendously tractable and quiet, then then diesel’s additional range would endear it as a thoroughly convincing tourer.

You know it’s not though, right?

 I mean, even the most advanced diesels still have a little John Deere about them a few seconds after cranking into action - don't they? Not this one.

This new 3l V6 turbodiesel is a cracking engine.

Offered in two states of tune, it’s bristling with technology and the only way you’ll know it’s diesel is when the fuel attendant tries to fill it up with anything other than a black nozzle - which won't fit through the mis-fuel device.

Featuring a long-stroke architecture, it’s the first compression ignition V6 to nestle a parallel sequential twin-turbocharger between the cylinder banks. Feeding the high-speed piezo injectors is a 2 000bar common-rail, enabling up to five injections per combustion cycle.

The new V6 diesel’s parallel sequential turbo set-up is unconventional in spinning a larger, variable geometry turbocharger most of the time, reducing pumping losses.

This is in contrast to other twin-turbo systems, which prioritise the smaller turbo, only actuating the larger unit when nearing peak power. Jaguar’s engineers claim the turbodiesel XF will spool up the smaller turbo within 300miliseconds as soon as engine speed passes  2 800r/min.

Beyond all the technical jargon, the new diesel engine produces very competitive output figures. In S trim, the 3l V6 turbodiesel generates 202kW at 4 000r/min, with the entry level diesel’s 177kW easily bests the 2.7 it replaces by some margin - a whole 25kW in fact.

Rotational force is the key feature of compression ignition engines, and here both S and standard 3l V6 units peak with round figures of 600- and 500Nm at only 2 000r/min. Jaguar’s claims average consumption of only 6.8l/100km, which is remarkable considering the XF is a 1.8ton car.

On the prowl

So, we know Jaguar’s engine design team has not slept much for the last couple of months, gauging the sheer volume of new technology brisling under the bonnets of the repowered XF range.

In tangible terms though, does all the newfangled technology translate to a more rewarding driving experience?

Jaguar set us about a circular route meandering towards the Magaliesburg, which considering the altitude, saw the new diesels obviously at an advantage over the 5l V8.

Both the diesels and V8 drive through the selfsame ZF six-speed gearbox, with the only difference being a shorter final drive ration on the compression ignition engines. Although the V8 picks up engine speed with a greater sense of urgency, there is precious little difference in real-world performance between the petrol and diesel models.

Jaguar claims the S diesel will drop 0-100km/h in 6.4 seconds, which is indecently rapid for an executive saloon you fill up with a black nozzled fuel pump.

The new 3l V6 diesel is uncannily quiet, even moments after start-up. When pressing on the abundance of torque propelling the car at medium engine speeds ensures secure overtaking acceleration, ideal for passing those lines of construction vehicles clogging up Gauteng’s road network currently.

Premium billing with proper heritage

XF’s appeal has been nearly perfected with the new engines.

These cars are design icons, with perfect thirds proportional balance to the front surfacing and tidily executed bonnet lines rounded off with a minimalist rear.

The interior, with its mood lighting playing off the contemporary design and materials has properly dragged Jaguar into the 21 century. Detailing is brilliant too.

Even the pop-up drive controller, which ensures a strikingly uncluttered centre console (reminiscent of the days when executive saloons had column shift selectors) remains novel, even on reacquaintence.

If you’re a rural entrepreneur or professional and need the range, the diesels are brilliant, yet South Africa’s suicidal variance in diesel fuel quality means good judgement is critical where you choose to fill up.

For most, I expect the 5l V8 will now make an even better alternative to the Germans than when XF was launched last year in 4.2l headline trim.

XF’s new engines finally resolve class leading performance to match the striking exterior design and brilliant balance of cosseting ride and crisp handling.

Best of all though, considering Coventry doesn’t build a SUV (unlike the Germans), you’ll never have to return a wave from somebody driving a five-door Jaguar, rotating 22-inch spinners…

XF 3.0 V6 Petrol    Luxury                  R565 000
XF 3.0 V6 Petrol    Premium Luxury    R599 000
XF 3.0 Diesel         Luxury                  R597 000
XF 3.0D S Diesel   Premium Luxury    R672 000
XF 5.0 V8               Premium Luxury   R755 000

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