Above: Jaguar brought its aluminum-bodied 2014 F-Type to this year’s Chicago Auto Show, hailing it as the heir to the iconic E-Type of the 1960s. It’s off to an auspicious start: The F-Type received the 2013 World Car Design of the Year award.

Aluminum unibodies improve fuel efficiency, enhance recyclability and decrease the company’s carbon footprint

September 2013 - Four of the five vehicles built by both Jaguar and Land Rover now incorporate all-aluminum monocoque body structures fabricated with light alloy sheet, extrusions and castings. Land Rover’s entry-level LR2 sport utility continues with a steel body on chassis, and Jaguar’s XF four-door sedan is built with a steel unibody. The latter is due for a redesign, and the smart money is betting on light alloy.

Take what you’ve heard about aluminum being a material for only the highest-end cars with a healthy dose of skepticism. Land Rover’s new Range Rover Evoque five-door SUV, the least costly with a full-aluminum monocoque structure, carries a price of $42,040. Its curb weight is a svelte 3,902 pounds, and it is rated at 20 miles per gallon city and 28 miles per gallon highway.

In its recent on- and off-road test, the television automotive magazine “MotorWeek” called the top-of-the-line Range Rover “the first all-aluminum SUV ever.” Weight savings are considerable; the Range Rover has shed 700 pounds for a curb weight of 4,918 pounds. Combined with an eight-speed transmission, fuel economy has been improved by 15 percent.

Now 14 mpg city and 20 mpg highway may not seem to be an astounding achievement. Those are the EPA figures for the normally aspirated Range Rover, and the ratings for the juggernaut 510-horsepower supercharged version are 13 mpg and 19 mpg. But be assured the 15 percent cut in fuel consumption is a commendable improvement over its competition. It is, “MotorWeek” said, “good for its class of luxury full-sized SUVs.” Reducing the weight of the body-in-white also allows the addition of the luxury options that Land Rover’s drivers demand.

Aluminum from the beginning

Using light alloys is not new for Jaguar and Land Rover. The first Land Rover, built in 1948, had its boxy, slab-sided shape formed from aluminum because of a shortage of steel in post-World War II Great Britain. And Jaguar, which began life in 1921 as the Swallow Sidecar Co., built its first vehicles with aluminum bodies over steel frames. Sir William Lyons’ company continued to use aluminum when it began building automobiles, including the SS-100. Swallow became Jaguar Cars Ltd. in 1945, and the first 275 copies of the iconic 1948 XK-120 roadster had aluminum coachwork. Subsequent versions continued with aluminum hoods and trunk lids.

It’s a supreme irony that, given the history of relations between Great Britain and India, two of England’s storied marques are now owned by an Indian conglomerate. Tata Motors, headquartered in Mumbai, is just one branch of a diversified company that controls everything from primary steel mills to the Tetley tea brand, and it rode to the rescue when Jaguar and Land Rover needed assistance. Tata has maintained a light touch on the management reins, allowing JLR’s designers and engineers to produce vehicles that have burnished the company’s reputation as a luxury brand that is respected for design innovation, engineering prowess and quality.

Mark White, chief technical specialist for body structures at Jaguar Land Rover, says the application of light alloys is driven more by the size of a vehicle than its cost. “I believe that the trend of using more and more aluminium for premium vehicles will continue over the next 10 years and that, to meet the CO2 glide path agreed by the automotive industry, more OEMs will have to apply further weight-saving methods, including greater use of aluminium across all segments. However, the larger the car the greater the challenge. Therefore, it is likely that larger cars will lead the weight reduction initiatives and the industry as a whole.

“As we have seen with many other technologies, the premium market tends to lead the way, with the rest of the industry following over the coming decade. I believe this will be the same with lightweight materials,” White notes.

Reducing the footprint

Lightweight materials shrink a vehicle’s carbon footprint throughout its life cycle. And aluminum isn’t the only weight-saving material under consideration. All options, including carbon fiber reinforced plastics, are on the table.

But CFRP have unique characteristics that make them less than ideal in a vehicle life cycle, White points out. CFRP are energy intensive to produce and currently have limited recycling potential. CFRP can reduce tailpipe emissions through reduced weight but do little to benefit the total life cycle. “Light metals offer a better value and lower carbon footprint solution,” he says.

Aluminum is an excellent replacement for steel in automotive unibodies, White believes. “[It offers] a 40 percent weight saving for the same performance,” he points out. “It is, therefore, an ideal material for skin panels and structural applications, very easy to recycle and the recycling infrastructure [is] in place, allowing us to use higher and higher percentages of recycled metal in our future products.”

The quest for weight reduction has not compromised safety. JLR has a five-star rating from EuroNCap for the Range Rover, which meets all global safety specifications, including roof crush standards. And JLR emphasizes that a large vehicle with reduced mass does less damage to a smaller vehicle in the event of a collision.

Riv-bonding

JLR’s crash test performance is due in part to its assembly technique. It combines structural adhesives and chemically nonreactive boron-carbide rivets that provide both strength and reduced emissions. White explains riv-bonding:

“We chose this route as opposed to other vehicle construction methods because ultimately we believe this offers a high-volume solution that will facilitate cycle times similar to that of today’s steel spot-welded vehicles. We have achieved self-piercing rivet cycle times very close to that of a spot weld and, when we take into account [that] we use between 3,500 and 4,000 SPRs relative to 5,000 to 6,000 spot welds, we have comparable hours per car for the body construction.

“We have also worked hard to ensure there is little or no additional vehicle build complexity, so we can use existing paint-shop and final-assembly facilities to minimize additional investment for our lightweight vehicle strategy.

“We have reduced the number of parts and increased the formability of the alloys to further reduce cost and weight. We also see big energy savings in the body shop with our approach.”

Because there is no welding, cooling water and air extraction for fumes are not required. The SPR guns use less energy than spot welders or laser/MIG welders, which reduces the carbon footprint of the fabricating facility

No increase is apparent in the bulk of Jaguars and Land Rovers with the advent of all-aluminum construction. White cites the example of aluminum A-pillars and door frames that are comparable in size to steel-bodied cars, with no compromise in safety.

A robust recycling infrastructure already is in place for aluminum, and there is the well-known 5 percent energy advantage of recycled aluminum compared to virgin metal. JLR’s target is 85 percent recyclability and 95 percent recoverability for all of its vehicles.

The question of repair

Light-metal skeptics point to vehicle repair as a perceived Achilles heel of aluminum. The cost will be somewhat higher, White concedes, but only for crash parts and fixed costs.

“Currently, the use of aluminium adds cost to accident repairs, mainly due to facility, tooling and material costs. Labor times are comparable to steel repairs.

“Jaguar Land Rover has ensured that repair standards, tooling and methods are common across both brands, therefore allowing our dealers’ operations to provide common repair facilities. Benchmarking of other OEMs enables our current Jaguar aluminium body shops to offer Land Rover repairs, and non-Jaguar Land Rover aluminium body shops can be approached to offer solutions with minimum investments.”

Other than higher material costs, White sees no downside to aluminium. “The durability of an aluminium riv-bonded body structure is at least as good as, and most instances better than, a conventional steel spot-welded body,” White says. “The added advantage of a lower vehicle mass helps in crash and durability, whilst an all-aluminium body structure is effectively inert to any sort of galvanic corrosion.

“Corrosion only becomes a factor when we have mixed metal structures, but the requirements for isolating aluminium from carbon steels or CFRP are well understood in the industry. As such, aluminium intensive vehicles will not only last much longer than steel bodies, they are more easily recycled at the end of the vehicle’s life.”

Aluminum technology is more than a means for engineers to meet fuel and emissions standards. It’s also a marketing tool, as Andy Goss, president of Jaguar Land Rover North America, made clear. He addressed the Midwest Automotive Media Association’s press preview kickoff breakfast at this year’s Chicago Auto Show, and his audience primarily was consumer-oriented journalists. But he spent considerable time detailing JLR’s use of light alloys and green manufacturing technologies, which he believes will attract sophisticated consumers—just the audience JLR targets. MM 

PROJECT 7 CONCEPT IS JAGUAR’S LATEST ALUMINUM EXERCISE

Aluminum construction continues at Jaguar with the Project 7 concept car, a study based on the company’s current 3,521-pound F-Type roadster. The 2013 Goodwood Festival of Speed in England was the venue for introducing the Project 7, and the number commemorates the seven racing victories amassed by Jaguar in the 24 Hours of LeMans from 1951 through 1990. That record includes victories in three successive years, 1955 through 1957 with the legendary D-Types. One novel feature: In carspeak, the Project 7 is a monoposto. It has a single-seat cockpit, like a Formula 1 Grand Prix car.

“The overriding dynamic aim when developing the F-Type,” says Ian Callum, director of design, “was ensuring connected feel; it’s a true driver-focused sports car. … Having achieved that for the road, Project 7 has given us a unique opportunity to go that little bit further. It’s visceral in every sense—its response, its sound and its sheer performance.” Mike Cross, chief engineer for vehicle integrity, emphasizes the Project 7 is a fully functional sports car. “The F-Type’s rigid all-aluminium architecture provides the perfect starting point, with power supplied by a 550-horsepower Jaguar V8 engine. … Jaguar’s sporting bloodline and innovative ambition are perfectly embodied by Project 7, both through its sensual design and its shattering performance.”

A zero-to-60 miles per hour time of 4.1 seconds and an electronically limited top speed of 186 miles per hour give the Project 7 near super-car capabilities. And the versatility of the F-Type’s unibody is evident in the fact that the concept car sprinted from first sketches to the Goodwood demonstration runs in only four months.

Photos: Jaguar Land Rover North America except where noted.

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