Hush-hush specialist media previews of new cars can be something of a marketing-led, frothy hype-fest. Not so Jaguar’s new XE sports sedan, shown in secrecy to this Automotive Engineering editor by the senior design and engineering executives who led the program.
Only now officially unveiled to the world at a London event, the detailed secrets (a few already drip-fed to the public to whet interest) of the coupe-style XE, can be revealed. They add up to a virtually totally new car, slotting into the company’s range below the XF and having some clear design and technology links to the F-type sports car including a twin-supercharged 3.0-L V6 engine option for the XE S.
Nick Miller, XE Vehicle Program Director, has overseen all aspects of the car. These include its 75%/25% aluminum/steel material mix. respectively; new modular vehicle architecture (MVA); sleek aerodynamics; integral link rear axle, and the new, modular 2.0-L Ingenium diesel and gasoline engine range (previously described at http://articles.sae.org/13353/).
There are also many technology fine points, including a laser head-up display and an All Surface Progress Control (ASPC), that applies sister brand Land Rover’s know-how to deliver “optimum traction” via cruise control at low speeds in extreme winter conditions—without the driver touching the pedals.
The ASPC system based on terrain response technology developed by Land Rover uses engine and brake electronic controls to achieve optimum traction; the driver simply steers. It can be used between 3.6 and 30 km/h (2 and 19 mph). Said Paul Atkins, XE Vehicle Integration Manager: “It provides a better performance than even the most skilled driver can demonstrate.”
Miller says a company mantra sums up the five-year-long program: “Better looks, better drive, better value.”
The five-seat, rear-drive, electrically steered XE enters production early next year as Jaguar’s stiffest (20% torsionally better than the XF), lightest [from 1474 kg (3250 lb)], and most aerodynamic (0.26 Cd) sedan ever. It is slightly larger than the BMW 3 Series, slightly smaller than an Audi A4. The cabin provides a “close-coupled” effect between front and rear, the driving position is lower than that of the XF and a little higher than the F-type. The rear seat squabs have been positioned low to provide headroom beneath a coupe-style roofline. The rear door apertures are as wide as possible.
New engines and vehicle architecture
The XE is claimed to be the first in the mid-size segment with an aluminum-intensive monocoque. The XE claims a world first for a car, using RC 5754 aluminum alloy, made predominantly of recycled material. Future JLR models will also use it.
The four-cylinder Ingenium diesel XE with 120 kW (161 hp) and 380 N·m (280 lb·ft) driving through a six-speed manual gearbox is expected to achieve an official combined fuel consumption figure of 3.8 L/100 km, with CO2 emissions of 99 g/km. (A lighter version of the established ZF 8HP eight-speed auto is also offered.) Service intervals are 33,000 km (20,500 mi) or every two years. The manual gearbox (Jaguar last offered a manual six years ago) has hollow shafts and pocketed gears, and rotational losses are down via the use of a semi-dry sump to reduce oil churn and drag by about 40%.
Jaguar is expected to announce several versions of the Ingenium diesel and gasoline engines. The V6 produces 250 kW (335 hp) and maximum torque of 450 N·m (332 lb·ft) to make 0-100 km/h (0-62 mph) in 4.9 s.
Design Director Ian Callum says the new MVA provided fresh design possibilities: “It is not a given platform but a very flexible architecture. The XE has a sporty profile (customers for this type of car are unforgiving, younger), a long hood with distinctive power bulge, and a cabin as far back as possible. Rear-wheel drive helps a lot towards better proportions.”
In a coupe-style sedan, packaging is always a tough call, and five seats were deemed a must.
Getting aerodynamics down to a specified Cd 0.26 was also a challenge, stated Callum: “It called for fine tweaking, with the smooth underfloor very important.” Making extensive use of CFD (computational fluid dynamics) and working closely with engineering from the outset of the project achieved the target. Some 1200 CFD simulations and 4 million processor hours went into designing the XE.
The design and engineering teams had a very ambitious philosophy: “Anything we can imagine, we can create!”
Dr. Mark White, XE Chief Technical Specialist, Body Complete, underlines the significant effects of using aluminum with the application of new alloys and also the huge benefits of starting a “clean sheet” project with the chance to optimize: “For example, interior space—particularly the rear seats. Great attention was also paid to the H-points and the position of the door opening structure. Importantly, the natural frequency of the XE’s body is not excited by the chassis or powertrain, the level of rigidity providing good NVH by resisting transmission of noise and vibration.” A new spray-on sound attenuation material reduces weight by 3 kg (6.6 lb).
White said 70% of material used in the body pressings are 6000-series high-strength alloys; the remainder 5000-series conventional alloys. Riveting and bonding is used as it has been since the first aluminum XJ in 2003, although the process is much quicker. The use of 6000-series for body sides has allowed a down-gauge from 1.5 to 1.1 mm (0.06 to 0.04 in). The bodyshell weighs 251 kg (553 lb). “The XE’s structure is absolutely at the cutting edge of what is achievable today,” stated White.
The first use of RC 5754 helps Jaguar towards achieving a target of 75% use of recyclable material by 2020. The XE uses 40 kg (88 lb) of recyclable plastics.
To provide a good mount for the axle, high-strength steel is used for the rear section of the bodyshell; it is also used for the door beams to provide added stiffness. The front end carrier and cross-car beam are magnesium. The best front/rear weight bias of the built-up car is 50/50.
The crash program involved 74 vehicle tests and more than 20 sled tests. Jaguar is expecting to achieve a 5-Star NCAP safety rating in Europe and the U.S. Extensive use is made of active safety technologies, and the car has a forward looking stereo camera.
A new version of Jaguar’s deployable hood for pedestrian protection is smaller, faster, and more responsive. There are now minimal hard points relative to external surfaces including the car’s underside.
To minimize turbulence, the XE has a rear diffuser to help equalize airflow under and over the vehicle. For the first time Jaguar uses air shields to reduce wheel arch drag, similar parts to those on its 1990s Le Mans race cars. Cooling vanes are used for the front brakes; an organic pad material reduces dusting on the wheel and cuts noise and vibration.
Integral link rear suspension
Details of the XE’s modular lightweight suspension includes the use of double wishbones at the front with a rear integral link setup, regarded by the company as delivering the required dynamics that a conventional multilink configuration could not.
Atkins said knuckles and bearings have been designed to give XFR (referring to Jaguar's high-performance mid-level XF sedan) levels of stiffness. Front knuckles are manufactured using a patented Cobra press process. It involves pressing from castings rather than solid metal billets. Slip fixings are also used for the first time by Jaguar. Typically, if a curb is struck, rather than damaging components, the fixings slip and can be reset by a dealer.
The integral link rear suspension provides longitudinal and lateral stiffness for “sports car like” handling and a “luxury ride.” It allows the use of bushings about 30% softer than those on the XE’s competitors, said Atkins. Dual-rate rear springs are of a lighter metal material than traditional types.
“'The best ride of any Jaguar’ was the statement we worked to in development; the first 50 m of travel should communicate the behavior that is going to be presented for the rest of the drive,” stated Atkins.
Jaguar's first EPAS
The use of EPAS (electrical power assisted steering) is a very significant step for Jaguar. “We had to ensure that it would deliver Jaguar’s trademark values,” explained Atkins. “Early EPAS systems could suffer internal gearing friction. We use active intelligence to compensate for this. It is the best steering we have ever had on a Jaguar, the software allowing an infinite ability to fine-tune the system.” It is speed variable and has “soft locks” to cushion limit of travel effects. It also has active returns for self-centering, as well as drift compensation for camber effect. EPAS helps reduce CO2 emissions by 2-3%.
Driver assistance systems include a laser HUD that provides greater clarity, is smaller, and a third lighter than similar systems. InControl infotainment systems include an 8-in touchscreen. "Plain speech" voice control is used. The car acts as a Wi-Fi hotspot, enabling multiple devices to connect to the Internet.
The XE represents part of a £1.5 billion JLR (Jaguar Land Rover) investment including an all-new purpose-built manufacturing facility at Solihull in the English Midlands.
Further details and specifications of the entire XE range will be announced at the Paris Motor Show in October.