Targeting the Teutons : Jaguar XKR

Car Specifications
Engine: 
5000cc Supercharged
Cylinder Layout: 
V8, 32 valves, DOHC
Top Speed: 
250 km/h (electronic limited) 280 km/h with Sports Pack
Transmission: 
6-speed ZF automatic with manual selection
0-100km/h: 
4.8 seconds
Power: 
510 bhp at 6000-6500 rpm
Torque: 
625 Nm at 250-550 rpm

photo-assay by Nick Dimbley

Had Jaguar only made the brilliant 510 bhp V8 for the XFR it would have been too myopic. The good news is this engine finds its way into the revamped XKR coupe and convertible.

This supercharged 5.0-litre V8 tagged the AJ-V8 Gen III's claim to fame is its efficiency, using less fuel to develop 510 bhp than did the old unit producing jus 416 bhp. We liked it in the slightly heavier XFR but in the lighter all aluminum XKR coupe the performance is noticeably peppier. It scorches to 100 km/h in 4.8 seconds just 0.1 second faster but in the real world it feels like a world apart.

 

Perhaps it is subjective thanks to the new, louder soundtrack of the exhaust system that plays a heavier version of what seems to be a refined multi-cylinder Harley bark an octave higher in pitch. The exhaust system may seem like a simple part but the development team sent an inordinate amount of time to get the exhaust signature right using both computer aided designs and full-scale trial set-ups. If one is wondering why it can be heard so distinctly inside the cabin it is because the engineers have devised a special device that ducts the intake note from part of the plenum chamber and connects it with the cabin allowing the XKR to be neighbour friendly on the outside but entertaining on the inside.

With its lower center of gravity and less compromised suspension the XKR develops higher mechanical grip from the same 20 inch tyres it shares with the XFR pressing you harder into the side bolsters and allowing some pretty late braking on the track. Astonishingly the Continental sourced 380mm disc brakes were every bit up to the task and felt they could really take the heat without the cost and complication of carbon-ceramic brakes. Equally important is how the brakes behave on the road producing good, reassuring bite and proper low speed progression despite its huge size.

The quicker steering racks employed by the XFR and XKR gives the sensation of more immediacy but never feeling nervous even at high speed which is a common failing with quick ratio racks. The XKR ventures into the 200 km/h zone with more visceral feedback than did the XFR as it puts the driver closer to the ground and planted on a firmer suspension, something it surprisingly shares unchanged with the XKR convertible. This allows the XKR convertible to feel even more enjoyable than the coupe inspiring a shade more confidence if at all possible.

Of course more than the XFR, the XKR allows you to get a proper flow through the curves stringing the actions of braking, turning and accelerating into and out of a corner in perfect overlap. The fully Adaptive suspension displays subtle differences between Normal and Dynamic settings but even on its Dynamic setting the Adaptive suspension never feels harsh and masochistically speaking it could do with a bit more stiffness but one needs to be reminded it is a Jaguar though it seems their new direction is to return to its sporting roots hence the first roll out models are the hardcore XFR and XKR models.

Unlike the first gen XFR, the XKR has held a long tradition within the hallowed halls of Jaguar beginning with the 1984 XKR. While not really a new XKR, the revisions apart from the new engine focuses the coupe tightly on what is important, delivering that special driving experience. What was special when built around the previous 416 bhp motor no longer cuts it when saddled with 510 bhp. The game needs to be moved up on many fronts.

While they have addressed the most obvious- the brakes, a host of changes to the suspension ensues as well. Spring and damper rates need uprating as does the kinematics of the bushings. Being a Jaguar necessitates another layer of difficulty because above all else it needs to retain a certain degree of comfort and refinement.

Dunlop has worked hard with Jaguar to satisfy these demands with their SportMaxx tyres. These special compound tyres help deliver remarkable ride comfort, low noise and sporty handling in one swoop. There are other OE suppliers like Pirelli but every single car in the test fleet was shod with this once very British tyre.

The all new supercharged 5.0-litre V8 has numerous technical innovations to reduce fuel consumption and CO2 emissions when driven on a daily basis. The biggest feature is the new direct injection system which allows accurate fuel metering to the nth degree. The engine could have possibly used a higher compresion ratio but the engineers thought it would be better to accommodate a wider range of fuel quality and temperature ranges than seek the ultimate maximum compression ratio yet still offering a competitive 510 bhp. The valve timing is now variable on both intake and exhaust cams with the oil pressure feed coming off the variation in the torque of the camshafts than keeping a parasitic load on the main engine oil pressure system.

So with the variable cam component, the engineers can play with overlap and at light or part throttle operation actually increase overlap to reduce pumping losses by increasing exhaust gas recirculation and suitably altering air-fuel mixtures. The result is a engine that helps the XKR drop CO2 down to 292 g/km below the 300 g/km mark. Like most modern high power engines torque is managed by the ECU to deliver a flat plateau of 625 Nm from 2500 rpm to 5500 rpm by controlling the pressure delivered by the new super quiet Eaton supercharger. Some might miss the mechanical whine but it does let you appreciate the new exhaust note rather more.

However what's better than the sound is the newfound alacrity of this engine, delivering a snappy throttle response, almost too quick for comfort in the Dynamic mode where the heightened responses expose the driver's shortcomings if the throttle is not modulated just right. Dynamic mode also controls the active suspension damping putting it onto a more aggressive map. However true to form the XKR is decently comfortable even in this mode. Any change is subtle because it is an active suspension, seeking the best setting for the situation 500 times a second.

To get the excellent ZF autobox into the mood one has to put the gear dial into “S” or Sport mode. The combination of that with Dynamic mode keeps the engine revs as high as possible and it also activates the appropriate downshifts pattern when one is slowing for a corner to be taken at speed. The computer senses the braking, steering angle and throttle rate to select the correct gear. Of course one can take over the shift duties with logically placed shift paddles on the steering wheel behind the three and nine position. Also to enhance braking there is a priming circuit to keep the pads closer to the disc to get that immediate bite upon application.

With 510 bhp lurking under the hood obviously things can get very sideways in a hurry especially in the rain and Jaguar is acutely aware of this. They have employed several traction optimizing devices in the car and the most intriguing is the electronically controlled rear differential that can vector the torque completely to either side depending on the traction needs. The next control layer would be the brake based traction control and finally if all else fails the reduction of engine power.

The severest test of any high powered RWD car would be trying to join the main road from a side street. In most high powered cars the traction control kills the power very obtrusively as one applies the power.

Try this in the XKR or even XFR and the result is so smooth and effective one does not even realize the power has been cut and the amount of acceleration possible even in the wet is simply stunning.

SPECIFICATIONS

ENGINE
CAPACITY : 5000cc, supercharged
CYLINDER LAYOUT : V8
VALVES : 32-valves, 4-valve heads
BORE X STROKE : 92.5 x 93 mm
COMPRESSION RATIO : 9.5:1
MAXIMUM POWER : 510 bhp at 6000-6500 rpm
MAXIMUM TORQUE : 625 Nm at 2500-5500 rpm

TRANSMISSION
TYPE : 6-speed ZF automatic
DRIVEN WHEELS : RWD

PERFORMANCE
TOP SPEED : 250 km/h (electronically limited)
0-100KM/H : 4.8 seconds

SUSPENSION
FRONT : Double wishbones
REAR : Double wishbones

BRAKES
FRONT : Ventilated discs
REAR : Ventilated discs

TYRES
TYPE : Dunlop SportMaxx
SIZE : f: 235/35 ZR 20, r: 285/30 ZR 20

SAFETY
ABS : Yes
AIRBAGS : 6
TRACTION CONTROL : Trac DSC

MEASUREMENTS
LENGTH : 4794mm
WIDTH : 1892mm
HEIGHT : 1322mm
WHEELBASE : 2752mm
KERB WEIGHT : 1753-kg
TURNING CIRCLE : 10.9m

Summary
The larger XFR is meant to be a Q-car and thus expectations are quite different though the overall characters and performance envelopes of the XFR and XKR are very close, but there is a clarity of purpose with which the XKR gets the job done putting the new XKR in contention with the 911. - photos by Nick Dimbley
Photos: 
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