French Connection

The announcement that Jeep’s owners, Fiat Chrysler Automobiles, intended to merge with French conglomerate PSA Group, custodians of Peugeot, Citroen and now Vauxhall, was perhaps one of the biggest automotive news stories of 2019.

The tie-in was set to create a car-making giant with revenues of €170 billion, while sales volumes of 8.7 million units would rank it as the fourth largest manufacturer in the world.

However, it will not be the first time Jeep has found itself under French control. In fact, one of the brand’s most successful ever models owes much to an earlier partnership with another famous Gallic marque - Renault.

If cars can be said to have parents, then François Castaing is undoubtedly the father of the Cherokee XJ. Jeep’s owners of the time, American Motors Corporation (AMC), convinced Renault to make a multi-million dollar investment in the company in return for lucrative access to the American market for the French firm’s passenger cars. To ensure their money was spent wisely, Renault installed Castaing as Vice President for Product Engineering and Development on AMC’s board.

Castaing was smart. He’d cut his teeth at Gordini where he’d risen to Technical Director, having started out building engines for Le Mans 24Hr racers. He saw the value in letting engineers cut through the bureaucracy of a large organisation, and would go on to create a new Product Lifecycle Management (PLM) process that would become the template for all automakers.

Traditional automotive development followed a regimented route, with the project handed from one department to another until a production-ready vehicle eventually emerged at the end. Castaing changed that.

He created teams of engineers that would follow the vehicle throughout its development, from planning to production, able to respond to challenges and resolve issues quickly. Computer-Aided Design (CAD) featured heavily in Castaing’s approach, with drawings and documents stored in a central database for easy access, and this dramatically reduced the time-to-market for new vehicles.

So successful was this new philosophy that when Chrysler later bought AMC in 1987, it rolled out Castaing’s process across the company. By the mid-1990s, Chrysler would boast some of the lowest development costs in the industry.

When Castaing joined AMC in 1979, design work on the new XJ had already started with a number of styling prototypes and clay models. Most SUVs of the era followed a long-standing formula of a two-door body atop a ladder-frame chassis, as did the SJ Cherokee launched in 1974.

AMC’s Vice President of Design, Richard Teague and his team had explored the idea of giving the XJ a more European look, and with Renault keen to ensure the new Cherokee would hold appeal outside America to maximise their return on investment, Castaing became its champion. The new Cherokee, then, saw many firsts.

For a start, it was designed in both two and four-door body styles at a time when even a full-size Chevy Blazer only offered two doors.

But perhaps the single most influential factor in the Cherokee’s development was a desire to keep it light. And that saw AMC adopt a technology that would place the Cherokee well ahead of its time.

While unibody or monocoque construction had been used for American passenger cars for some time, most trucks and 4x4s stuck resolutely with the concept of a separate chassis. That gave the strength needed to withstand the stresses and strains that go with off-road use, but also added considerable weight and was bad for fuel economy.

Gas prices in the US by this time were only heading in one direction, and with the impact beginning to be felt on the auto industry’s bottom lines, it was clear a new approach was needed.

Ditching the separate chassis, AMC’s engineers integrated the frame rails into a body structure that incorporated approximately 3,200 welds, making it both lightweight (saving almost 1,200lbs) yet incredibly rigid.

It was more compact, too. Compared to the outgoing SJ, the XJ was 21 inches shorter, seven inches narrower, and three inches lower. Yet despite this, the new Cherokee was a triumph of interior packaging, offering almost 90% of the cabin space of the old model.

There were other benefits. Not having a bulky separate chassis resulted in increased ground clearance, while new ‘Quadra-Link’ coil-sprung front suspension gave not just a markedly better ride, but greater axle articulation, too.

With its lightweight uniframe design, Jeep could afford to offer the Cherokee with a smaller, more economical engine, and so began a parallel project to develop a new 2.5-litre four-cylinder powerplant. Many of the new engine’s dimensions such as bore spacing were selected so that existing engine tooling could be reused, while the location of components such as the oil filter and distributor were standardised to match Jeep’s venerable straight-six.

Chief engineer Roy Lunn was rightly proud of the new engine:

Unlike most engines available today, ours was not designed originally for passenger cars and then adapted for trucks. We specifically developed it with our Jeep vehicles in mind. That’s the reason that performance and durability were of such prime consideration from the very beginning.

Despite its modest 105hp in single carburettor form, it developed 132lb/ft (179Nm) of torque at just 2,800rpm - and would do so all day long.

So right-first-time was it that it remained in production until 2002, while its sibling the 4.0-litre, itself a version of the 2.5 with two extra cylinders, carried on until 2006 having earned a reputation as one of the greatest engines ever built.

For the Cherokee’s motive power, Renault would again make a contribution.

Both the 2.5L and 4.0L used a Renix (Renault/Bendix) microprocessor-controlled engine management system that was considered remarkably advanced for its time. It included a knock sensor to detect detonation, and this gave the system the ability to precisely adjust ignition timing for each cylinder to prevent pinging, regardless of engine load or fuel octane.

Having been designed prior to the creation of the OBD-I legislation that would later mandate an on-board diagnostics port, it was replaced by Chrysler’s own system in 1991.

At launch in 1984, the new Cherokee attracted almost limitless praise. It was named 4x4 Vehicle of the Year by all three leading American off-road magazines, a ‘triple crown’ distinction never before achieved.

With a starting price of just $9,995, the competition had nowhere to go. Motor Trend magazine went as far as to say:

Today’s XJ-series represent such an advancement over the previous vehicles that there’s little point in even talking about comparisons.

Perhaps not surprisingly, Jeep’s sales figures doubled that year.

In 1985, the XJ gained shift-on-the-fly capability for its full-time four-wheel-drive system plus the option of a Renault-sourced 2.1-litre turbodiesel, while 1986 saw the Cherokee line extended with the arrival of the Comanche pickup.

The new 173hp 4.0-litre straight-six arrived in 1987, as did a luxuriously-equipped Limited model that briefly became one of America’s most stolen vehicles, so badly did people want one.

By 1987, the world and his dog wanted a new Cherokee. The new Wrangler was about to launch, and dealers could sell every Jeep they could get their hands on several times over.

Not only that, but Jeep was generating record profits, too. AMC notched up a billion dollars in sales in the first quarter of 1987, earning it a profit of more than $23 million.

Yet this might seem a strange time for Renault - having invested heavily in loss-making AMC over the last eight years and on the cusp of finally receiving its payback - to pack up and go home.

Tragically, Renault Chairman George Besse was assassinated by communist terrorist group Action Directe in November 1986, and the French company retrenched to focus on domestic issues.

AMC was sold to Chrysler for the bargain price of $1.7 billion, with Jeep unmistakably the jewel in that particular crown.

But Chrysler CEO Lee Iacocca’s dollars hadn’t just bought him a profitable business, a world-famous brand with a stronger-than-ever product line-up, a building full of talented engineers like Castaing, or a brand new production facility at Brampton, Ontario, built with Renault’s money.

Waiting in the wings was another new SUV. Designed by future-conscious AMC engineers as the eventual replacement for the XJ, it was finally unveiled to the public as the thinly-disguised Jeep Concept 1 of 1989.

Held back by Iacocca, it eventually became the 1993 Grand Cherokee (ZJ). It shared much with the XJ it was originally intended to replace, most obviously the indestructible 4.0-litre engine and the rigid yet lightweight uniframe construction.

Yet with XJ sales showing no signs of slowing any time soon, Chrysler executives wisely chose to offer the two products side by side. Over the next six years, the ZJ would sell nearly 1.7 million units.

Just as the ZJ was launching in America, the XJ came to the UK in right-hand-drive form. Eager customers forced over-inflated deposits into their dealers’ hands, and when second-hand examples eventually trickled onto the auction circuit, they consistently sold for more than their new sticker price.

By the time the XJ Cherokee was finally retired in 2001, having outlived the model that was intended to replace it, it had been in production for almost 18 years with only one major refresh. Nearly three million units had been produced, and even in its final months it was still Jeep’s second best-selling model.

Not a bad return on investment, then.

Merci, François.