在汽车行业，“运动”是一个已经过于泛滥的字眼。在广告中，常会看到将“轿跑”和“GT”凑在一块，试图用类型化的手段给给产品增光的做法，“运动”一词也经常被这样滥用。

因此，当捷豹的高级工程主管试图告诉《汽车工程杂志》，他们将在2016年全新推出的轻量级、高性能高端中型XF是一辆“运动型轿车”时，他们其实想说的是：这辆车不仅能在西班牙北部的高难度路面上行驶，而且还能在纳瓦拉赛车场上驰骋。

XF搭载着从F-type继承而来的279 kW (374马力)， 460 牛·米 (339-磅·英尺) 4.0 L V6涡轮增压发动机，即便驾驶员不是专业赛车手，只是本文的记者而已，这辆车也能够在高速行驶的状态下完美展现“轿车”与“运动”是如何完美结合的。这辆车以沉着冷静的表现出色地完成了试驾任务。

新款XF（查阅）同样可以搭配捷豹全新的Ingenium 2.0 L四缸柴油发动机，其中采用的是博世1800bar（26.1 ksi）的共轨喷射系统，它的功率输出范围为120-132 kW（161-177马力）。第二种配置的XF名为“R-Sport”。

如果撇开名字不谈，仅从工程角度考虑，这辆车是否真的可以被称为运动型轿车？尽管下定论仍需谨慎，但答案是偏向肯定的。

必须达成的要求

当捷豹决定研发这款新车的时候，工程师们面对的“必须达成的要求”看上去的确令人望而却步。但正如汽车工程主管Ian Hoban和发动机规划与策略高级经理John Pepperell所说的那样，最终结果达到了他们的预期。

与2007年推出的风格张扬的XF相比，新XF呈现出以下变化：用铝合金制作的车身框架，使整车质量轻了190 kg （419磅）；抗扭硬度提升了28%；空气动力效率达到0.26Cd；轴距加宽51 mm（2.0英寸），车身总长缩短7 mm （0.3英寸），因此车身包裹性更出色；最后还有彰显高端本色的车内与车外设计。机械方面的改动包括：一体化连杆后悬架；可提供双轮驱动和全轮驱动两种模式；电动助力转向系统（EPAS）；多种发动机可供选择，其中包括一台最高扭矩为700 牛·米（516 磅·英尺）的3.0L V6柴油发动机。

在全车3194个部件中，有2669个是经过全新设计的。

“新XF和XE使用的基础底盘是相同的，”Hoban表示。“我们认为，双叉骨前悬架和铝合金一体化连杆后悬架是保证操控性能与高端驾乘舒适感的最佳组合。”

捷豹在车辆上运用铝材料的经验已累计超过15年。“在铝材料的设计和制作方面，我们总是在挑战极限，”Hoban解释道。“A面是用铝蒙皮板制作的，车窗使用的是铝冲压件，还有车辆基底上采用了厚度各不相同的铸铝件，如前悬架的基座等。技术上难度极高的铝制车身侧围是一整片板材，每片重量不足6 kg。”

高强度镁铸件被用于制作XF的前架和横梁，在B柱等抵御侧面碰撞的关键部位还使用了超高强度硼强化工艺。

捷豹每次推出新传动系统的时候，Pepperell都从最初阶段就开始参与，在XF项目中也是如此。在初期工程规划中，他就将生产与制造策略纳入了考虑。

“在这一阶段，我们需要为发动机设定技术目标，其中包括动力、扭矩、细化、耗油量、排放等。我们会研究现有的技术，并思考还需要哪些新技术，”他阐述道。“我们有一个团队负责监控外部市场，评估竞争对手可能发展的方向，根据这些信息来决定我们的定位。接着我们将定位转化为工程规范，寻找一个全面综合的解决方案，并在此过程中思考各方面的问题，如设计的复杂性等。”

这一阶段完成后， 在捷豹路虎已工作了27年的Pepperell就会和团队一起将方案转移给项目实施团队，后者负责产品的具体工程设计：“对一台Ingenium这样的全新发动机而言，这一阶段将花上3-4年的时间。”此后便是一个接一个的研发阶段了。

在捷豹，开发一款新型发动机时还需考虑一个极其重要的方面：标志性声音。而且Pepperell坚定地认为，这项工作十分重要，马虎不得。在大多数情况下只要设计好排气系统就行了，但他也承认，小型柴油发动机比较困难，需要大量的实践：“坦白说，最小型的柴油机就是达不到这个效果。”

采用主动电子声音系统是否能解决这个问题？捷豹路虎已经在探讨这一可能性了。但如果声音听起来不够真实，那他们是不会使用的，Pepperell解释道。

XF具有具有一个形状可以改变的涡轮增压器（三菱MHT）、功率为132 kW的Ingenium柴油发动机。确实，这些特点有时候听起来与XF这样的车不太匹配，好在转速为1750-2500 rpm时最高可达430牛·米（317磅·英尺）的扭矩能帮上一点忙。与这台发动机搭配的是ZF八速自动变速箱。

700牛·米发动机

然而在XF的柴油发动机选项中，有一台V6发动机。它由Ford/PSA研发，不仅声音“恰当”，而且峰值扭矩可达700牛·米，它在新XF所有动力系统中给人留下了最深刻的印象。新XF的V6发动机的输出功率从202提升至221 kW（271至296马力）。在欧洲混合循环测试中，XF只需5.8秒就能加速至97 km/h（60 mph），此外它的燃耗仅为5.5 L/100 km，二氧化碳排放为144 g/km。

标准极高的驾乘和操纵方案，是几十年来多款捷豹车型的重要卖点，而XF在这方面取得的成绩比以往还要出色许多。

汽车动力工程经理John Darlington将XF的一体化连杆后悬架设计（为F-Type研发并被XE沿用）称为驾乘/操纵方面的“一颗明珠”。

此外，他还强调了在XF上使用的“下一代”减震技术的重要意义。在城市中驾驶时，一个额外的阀门可将部分机油绕过活塞中的主阀门，以减少阻尼力并使驾驶更为顺滑。当车辆在城外高速公路上行驶时，这个额外的阀门将闭合，让所有机油流经活塞，使驾驶更为稳健。

在XF的V6柴油发动机中安装了一个可调节的动态系统（定制的油门映射、变速箱换挡策略、转向感觉和适应性动态性能设置等），而且能通过触屏进行控制。

捷豹的所有这些努力，都让XF足以当得起“运动型轿车”这一美誉。

作者：Stuart Birch

来源：SAE《汽车工程杂志》

翻译：SAE上海办公室

Jaguar’s making of a sports sedan

“Sport” is a much abused word in the automotive industry. Like “coupe” and “GT” together with other attempts at glorification through categorization, it is open to abuse.

So when Jaguar’s senior engineering executives wanted to demonstrate toAutomotive Engineering that its new, mid-size, lightened, aerodynamically efficient, premium 2016MY XF really is a “sports sedan,” they illustrated the point not only on very demanding roads in northern Spain but also on the fast Circuito de Navarra racetrack.

With the supercharged 279-kW (374-hp) 460-N·m (339-lb·ft) 4.0-L V6 engine from the F-type tucked under its hood, the XF was able to show how to convincingly link, at high speed, the words “sedan” and “sport” even with this editor (with no race driver pretensions) in control. It tackled the task with a composed and tidy aplomb.

But the new XF (previously described at http://articles.sae.org/14038/) is also available with Jaguar’s new 2.0-L four-cylinder Ingenium diesel—using Bosch 1800-bar (26.1-ksi) common-rail injection system—with power outputs from 120 to 132 kW (161 to 177 hp), the latter offered in “R-Sport” configuration.

In engineering terms could that, despite its nametag, also be termed a sports sedan? The answer, with one caveat, is in the affirmative.

“Must” list

When Jaguar set out to create the new car, the “must” list of criteria that its engineers had to meet may have seemed daunting, but the result, explained Vehicle Engineering Director Ian Hoban, and Senior Manager Engine Planning and Strategy John Pepperell, is in line with expectations.

Compared to the outgoing XF introduced in 2007, these include a weight loss of up to 190 kg (419 lb) thanks to an aluminum-intensive architecture; torsional stiffness up by 28%; aerodynamic efficiency of 0.26 Cd; improved packaging on a 51 mm (2.0 in) longer wheelbase but 7 mm (0.3 in) shorter overall length; and external and internal design that marks it out as a premium product. The mechanical side includes integral link rear suspension; two- and all-wheel-drive versions; EPAS (electrical power assisted steering); and a very broad engine spread—there is also a 3.0-L V6 diesel with maximum torque of 700 N·m (516 lb·ft).

Of the car’s 3194 part numbers, 2669 are new.

“The new XF shares its fundamental chassis aspects with the XE," said Hoban. "Double wishbones front and aluminum integral link rear suspension we believe are the best combination for handling and premium-level ride comfort.”

Jaguar has accumulated 15 years’ production experience of aluminum throughout its vehicles. “We work at the limit of what is feasible in regard to design and manufacture using the material," said Hoban. "Aluminum skin panels are used for A surfaces, aluminum extrusions for sills, and aluminum castings of varying thicknesses for the foundations of the car such as its front suspension mounts. Technologically challenging aluminum bodysides are single panels, each weighing less than 6 kg.”

High-strength magnesium castings are used for the XF’s front-end carrier and cross-car beam, with ultra-high-strength boron reinforcement, in particular its B-posts for side-impact protection.

Pepperell begins his involvement with all the company’s new powertrains at a very early stage—as he did with those for the XF. That involvement concerns the embryo engineering programs in terms of production and manufacturing strategy.

“It includes technical target setting for the engines in terms of power, torque, refinement, economy, emissions—looking at what technologies there are and what we need,” he explained. “We have a team monitoring the external market place, assessing where we think competitors are going and where we consider we should be positioned. Then we have to translate that into an engineering specification, while considering aspects including complexity as we find the holistic, overall solution.”

That accomplished, Pepperell, who has 27 years’ experience across JLR, and his team hand over to a program delivery team who are responsible for the detailed engineering of the product: “Which for a brand new engine such as the Ingenium will take three to four years.” After that comes the serial development phase.

At Jaguar, another significant element in the development of a new engine is its aural signature, something that must never be subject to palliative action, insisted Pepperell. Much can be done by engineering the exhaust system but he admits that is difficult when developing a small diesel and there is a need for pragmatism: “Frankly, the base diesel will not achieve it.”

Could an active electronic sound system provide a solution; it is something that has been discussed within JLR. If it isn’t authentic it won’t happen, he explained.

Experienced in 132-kW form, the Ingenium diesel, with variable geometry turbocharger (Mitsubishi MHT), does sometimes sound a shade out of place in such a car as the XF, although maximum torque of 430 N·m (317 lb·ft) from 1750 to 2500 rpm helps. It is complemented by a ZF eight-speed auto transmission.

700Nm

However, one of the XF’s diesel engine options is a V6 diesel. Developed from aFord/PSA unit, it does make the “right” sound, and with 700 N·m on tap is a very impressive part of the new model’s powertrain repertoire. For the new car, the V6’s performance has been upped from 202 to 221 kW (271 to 296 hp). It gets the XF to 97 km/h (60 mph) in 5.8 s and achieves a fuel consumption of 5.5 L/100 km and 144 g/km CO2 emissions on the European combined cycle.

Ride and handling solutions that provide very high standards for both have been major selling points for most Jaguars for many decades, and the XF achieves that target far more convincingly than its predecessor.

John Darlington, Vehicle Dynamics Engineering Manager, regards the XF’s integral link rear suspension design (developed for the F-Type and also used in the XE) as “our jewel in the crown” with regard to ride/handling.

He also underlines the significance of the XF’s “next-generation” damper technology. For city driving, an additional valve permits some fluid to bypass the main valve in the piston, so reducing the damping force and smoothing the ride. As vehicle speed builds away from the city, the valve closes, forcing all of the fluid to pass through the piston to firm the ride.

On V6 versions of XF, a configurable dynamics system (tailored throttle mapping, transmission shift strategy, steering feel, and adaptive dynamics settings) is fitted and controlled via a touchscreen menu.

All of this is part of Jaguar’s determined aim to create a car that can carry convincingly the appellation: sports sedan.