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BorromeodeSilva’s Mustang STL1 restomod is an all-terrain Italian stallion

Milan-based design studio BorromeodeSilva returns with the Mustang STL1: an all-terrain tribute to the most iconic American Muscle car of them all!

After hitting it out the park time and time again with the likes of the Automobili Amos Futurista and Safarista, the Nardone 928, and the Eccentrica Diablo, Carlo Borromeo — creative director at Milan-based design studio BorromeodeSilva — has turned his sights away from Europe to the most legendary American muscle car of them all: the Ford Mustang. As Carlo puts it: “The Mustang is THE muscle car. It’s the first, it’s the most meaningful, and at the end of the day, it’s the number one muscle car. We don't care what Vin Diesel has to say.”

However, it wasn’t just the Mustang’s icon-status that earned it the restomod treatment; even the coincidental tie-in with the Mustang’s 50th Anniversary this year wasn’t planned. This really is a passion project for Carlo: a tribute to one of his greatest personal adventures, in what he considers the ultimate road trip car. In 2008, he fired up his 1968 Mustang Fastback in New York, and didn’t stop until he reached Buenos Aires as part of a mission to return his pride and joy to his mother’s home. During this endless journey down the Panamericana, Carlo and his 1968 Fastback traversed almost every landscape imaginable, from the altitude-sickness-inducing heights of America’s mountain ranges, to its picturesque crystal-white beaches, all the while envisioning what his dream reinterpretation of the Mustang would look like.

Over the past few years, the BorromeodeSilva design team has secretly been honing the STL1, but where do you begin when reimagining one of the USA’s greatest creations? “We start every project with a playlist,” says Carlo. “A lot of it is about the culture of the moment and where the car comes from. In this case, the playlist is about this trend in Italy from the 1960s and 1970s. A lot of singers would take American songs and re-write the lyrics in Italian, and that’s exactly what we’ve done with the STL1.” As for the name, STL1 can be read as “Stallone,” a nod to the original Italian Stallion. 

Carlo describes the STL1 as a “Fastback Mustang Safari” and he and his team went to great lengths to improve its off-road capabilities. In fact, the car features a brand new 1006 automotive grade steel body with a shell that is thicker and stronger than original, while retaining the exact shape. Crucially, this means very little of the donor car needs to be used beyond the VIN number, greatly reducing the cost and complexity of creating this restomod. 

The whole side profile of the body is narrower for extra ground clearance, with squared off wheel arches to help the lines flow on this shallower form-factor. The front and rear overhangs have been reduced to improve angle of attack and descent when off-roading, while the number plate has been relocated to the base of the would-be-rear windscreen. One of our favourite details has to be the completely re-designed high performance exhaust, where the exhaust tips have been integrated into the Mustang’s iconic three-bar rear lights. 

To ensure no landscape on earth can impede the STL1’s stampede, the team have upgraded the suspension with high performance billet coil-over shocks, tubular upper and lower full A-frame style control arms at the front, and completely redesigned upper and lower tubular heavy duty rear control arms. To help it stop on a dime, the front features drilled and slotted 11” brake disc rotors paired with heavy duty aluminium callipers, with 10.5” inboard-mounted units at the rear, à la the Alfa Romeo SZ. 

Behind the redesigned front end with its integrated rally-style fog lights sits the heart of the STL1, a 5.0-litre Road Runner Coyote V8, boasting a forged steel crankshaft, forged aluminium pistons, CNC ported cylinder heads, and a high-flow intake manifold taken from the 302R racecar. In addition, the engine was fitted with a revised camshaft with a high lift exhaust profile, resulting in a mighty 444 horsepower at 7,400 rpm and 380 lb-ft of torque at 4,500 rpm. 

Of course, the STL1’s party piece is its hand built, exposed roll cage, designed to mimic the roofline of Carlo’s own 1968 Fastback. “The Fastback is the quintessential Mustang,” according to Carlo. “Some might disagree; most people think the Coupe is the original and the Fastback is the variation, but to me it’s the other way around.” Peering through the artfully-designed roll cage, you’re welcomed by a typically outstanding BorromeodeSilva interior. A brand new digital dashboard, a sporty steering wheel, and new seats are the highlights, but there are hundreds of little details waiting to be customised to any potential customers’ wishes. 

On that note, we should discuss BorromeodeSilva’s plans for the STL1’s production. As it stands, the team intends to build just one of these untamed Mustang restomods, but the goal, naturally, is to build far more. If you’ve been dreaming of taking the ultimate off-road muscle car on an adventure of your own, these renders could be just the start of your journey, so don’t hesitate to get in touch with the BorromeodeSilva team via their website to start your STL1 adventure!