At last here is a really hot Jaguar sedan – the XFR, capable of 0-60 mph in 4.7 seconds, and the standing quarter mile in 13 seconds. This new
Jaguar XFR is a real flyer. With a few aerodynamic aids to keep the car on the ground, an XFR has been timed at
225 mph on the salt flats in the USA. The acceleration may not be quite up to that of the brute power of the 6.2 liter Cadillac CTS-V, but this is a might fast car with handling to match.
To suit the sporty image the XFR has a restyled front end with wide air intakes low down at the sides and new wheels. Otherwise, the car is based on the elegant XF shell, with all the trimmings the less powerful models have.
But with 90 bhp more than the old XF SV8 the XFR is much quicker than the previous models, and has the handling to match.
Super styling in wedge coupe
The Jaguar XFR looks great, and those side air intakes act as splitters, improving aerodynamics. The upward wedge line works well, as does the coupe-like fastback, cunningly shaped to conceal the adequate space in the rear of the car.
An advantage of the high tail is that the trunk is larger, but rear vision is not brilliant. Vertical slots behind the front wheels hint at the power within. The rear end is smart, too, like a taller Aston Martin.
Low drag
Jaguar claims that the XFR is completely balanced aerodynamically, with zero front and rear lift at speed. Also, the XF is slippery – it has a good drag coefficient of only 0.29.
When you press the start button on the center console, the rotary knob for the gear mode pops up. To select what you want, you turn it through P, R, N, D and Sport. Behind the knob are buttons to disable the stability control which has two different levels of control. Shifting is by paddles, there being no gear lever of course.
Jaguar's new V-8: 510 bhp to give stunning acceleration
At the heart of the car is Jaguar's AJ-V8 Gen III 5.0-liter V-8 engine which prodcues 510 bhp at 6,000-6,500 rpm, with maximum torque of 461 lb ft (625Nm) all the way from 2,500 to 5,500 rpm. This is interesting because the proponents of modern turbos say that a wide spread of maximum torque is one their advantages. Not so, it seems.
In fact, this is a sixth-generation Roots-type twin vortex blower. Which works through a pair of water-cooled intercoolers. Jaguar says that the new blower is 16% more efficient than the old one and is virtually silent – you might actually miss that distinctive supercharger whine.
This new engine, which has been a few years in development, are based on a high-pressure aluminum diecast cylinder block, and cylinder heads cast from recycled aluminum. The crankshaft is a spheroidal graphite casting, while the connecting rods are steel forgings.
Overall, the engine is about one inch shorter to the old one, and a little lower, owing to changes in the intake system.
The main feature, though, is the direct injection system. Jaguar has opted for multi-hole injectors mounted in the middle of the cylinder heads. Fuel is injected at 150 bar – about 2,200 lbs per square inch – which ensures good distribution and rapid combustion at low speeds. This high-pressure injection results in a cooler chamber which allows the use of higher compression ratios – 9.5:1 for the supercharged engine – and more power.
Variable valve timing
Variable valve timing in which the opening point is advanced or retarded according to conditions is used on all four camshafts. In addition, the naturally aspirated V-8s get two-stage valve lift. Each camshaft has three cams per valve, and a two-piece tappet – similar to the Porsche system.
At low lift – 0.22 in (5.5 mm) and 214 degrees opening period – the low-lift cam is actuated by the central part of the tappet, and at higher speeds, the system switches to the outer part of the tappet, so the high lift cams, which give 0.41 in (10.5 mm) lift and 250 degrees of opening. The speed of switching depends on the load.
New torque sensing electronically controlled diff
To handle the power of the new engine, Jaguar has moved one step forward in the use of electronics to help the handling in emergencies, but to give the driver more fun, with the option of controllable oversteer. Hey, this is radical! Most car makers are so concerned about 'safety' that they build in a lot of understeer, which is actually unsafe at the limit. Not Jaguar; they know more about handling than most, and the engineers are allowed to use their skills.
To start with, there is a new type of traction control, which is really a torque-sensing limited slip differential, but unlike those in use elsewhere, this is under electronic control and is switchable, so it does not affect the smoothness of drive at low speeds, such as when manoeuvring the car into a tight space.
The system consists of a multi-plate clutch and ball-and-ramp mechanism, under electronic control, and when one wheel slips, the torque is sent to the wheel that is still gripping in the proportion required to suit the overall situation. It is switched off when not needed. This is quite different from a conventional traction control which merely stops the torque going to the slipping wheel, slowing the car down.
And progressively variable damping with the option of oversteer
Thie new diff is combined with what Jaguar now calls Adaptive Dynamics. This is actually damping that can be adjusted progressively between very soft for low speed cruising to very hard for cornering very fast on undulating roads. A controller analyses the motions of the body 100 times a second – yes that often. The system detects roll, pitch, and diagonal pitch and adjusts the damping forces accordingly. In other words, if the car is starting to roll, the dampers on the outer wheels are progressively stiffened to limit roll. Similarly under brake dive, the front dampers are stiffened. Therefore, the car rides flatter than in the past.
In addition, the system increases the damping rate progressively but quickly as the wheel nears the bump stops, to prevent crash-through. The idea is that the ride maintains that renowned Jaguar suppleness, while controlling the body movements through damping.
There is also a stability control as part of Dynamic Mode, and when the stability control is switched off, the car is set up to allow controllable power-on oversteer – well that's what they say. Sounds like fun to me. Overall, a significant improvement, and ideal for a car like the Jaguar XFR, which is a very quick if rather overweight muscle car. A welcome addition to the range, and good value, too. Sorry about the black images.
