Jaugar XJ

Having introduced a host of new technologies for the 2012 Model Year and following the two new highly-efficient forced induction petrol engines announced earlier in the year, Jaguar is once again broadening its global product offering and improving customer choice with its 2013MY XF and XJ ranges.

The acclaimed eight-speed ZF automatic transmission first introduced to the XF range last year to complement its smooth, powerful turbocharged diesel engines is now made standard across the entire XJ and XF range for all petrol and diesel powerplants. The eight-speed transmission is allied to Jaguar's Intelligent Stop/Start system on all turbodiesel and V6 and V8 petrol engines (market dependent).

"The engineering target in developing the 2013MY XF and XJ powertrain range was to optimise efficiency and enhance choice, while never compromising the effortless performance that is an inherent and vital characteristic in all our cars. Through intelligent use of forced induction, eight-speed transmissions and, where appropriate, Stop/Start technology, each derivative in the new XF and XJ ranges meets that enhanced efficiency goal while offering the performance thrill expected of a Jaguar." Ron Lee, Group Chief Engineer, Powertrains, Jaguar Cars

Following its introduction on the 2.2-litre i4 and 3.0-litre V6 Turbodiesel engines for 2012MY XF saloons, the eight-speed ZF transmission is now extended across the entire XF and XJ ranges for the 2013MY offering better economy, reduced emissions and smoother acceleration compared to the previous six-speed equipped models.

For all installations the transmission's operating software has been specifically tuned to ensure it perfectly matches the power delivery of the engines to which it is mated and offers the sporting feel, precision and smooth shifting expected of a Jaguar.

With both a wider spread of ratios and more even spacing between them, the gearbox provides more seamless acceleration both from rest and when overtaking, while fuel consumption at high speeds is reduced. Gearshifts are executed in just 200 milliseconds while driver intervention is possible through the use of steering wheel-mounted paddles which allow multiple downshifts, allowing the desired gear to be selected almost instantaneously.

The use of lightweight, compact components including a rear differential with an aluminium casing means there is no weight or packaging penalty when compared with the outgoing six-speed models, while efficiency is improved through the use of an improved pump design and greater control of the gear elements.

Offering further efficiency improvements is Jaguar's Intelligent Stop/Start system, which is now fitted - according to market - to all diesel engines and the V6 and V8 petrol units. The system is able to shut down the engine in just 300 milliseconds after the car has come to a halt, allowing for fuel consumption improvements of around 5%.

No driver intervention is necessary; a complex system of control algorithms govern when the Stop/Start should function according to a number of operational parameters including engine, ambient and cabin temperatures, whether the vehicle is fully at rest, vehicle power requirements and so on. A green 'ECO' symbol on the dashboard lights up when the engine is shut down by the system.

Having come to a halt and shut down the engine, the Intelligent Stop/Start system is able to restart smoothly in less time than it takes for the driver's foot to release the brake pedal and depress the accelerator. It does so by utilising a Twin Solenoid Starter (TSS) mechanism that features its own secondary battery to ensure that in-car systems requiring power are not affected. The unique advantage of the TSS system is that it is able to restart the engine even while it is still in its run-down phase, allowing for 'change of mind' functionality, for instance if the car is coming to a halt at a junction but then a gap in traffic appears.

Source: Jaguar press

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