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Who Builds a Period Hot Rod out of a Gullwing Mercedes? This Guy!

David Conwell | Hemmings.com | Published on 1/8/2025

“There’s 1,400 of these. In the general scheme of things, they’re not that rare,” says Robert Webster, owner of this 1955 Mercedes 300 SL coupe. Rarity is, of course, relative. They only built 1,291 Kaisers in 1955, and most people would tell you those are pretty rare, but when you consider that unlike a mass-produced American sedan, the race-bred 300 SL with its distinctive gullwing doors, was a special car from new and survived in an accordingly large percentage, he’s not wrong.

Moreover, most of those survivors have at this point been restored to factory perfection or preserved in some fashion and arrested between originality and decay. Almost none of them have been modified and fewer still modified to reflect the modifications of the period when they were still popular and viable sports cars rather than collector’s items. The muscle-car crowd calls this “Day 2” style. Fans of pre-World War II Fords call it “traditional hot rodding.” We at Hemmings Classic Car call it all “period modified,” and we were tickled when, in January 2024 at the Arizona Concours d’Elegance in Scottsdale, we first heard and then saw the circa-1965 style that Robert has applied to his Mercedes.

Robert’s a fairly young guy, who wasn’t around yet in 1955 or 1965, but he’s got an appreciation for the nitty-gritty particulars of cars. “When I was 18-19-20 years old,” he says, “I was really nerding out about JDM [Japanese Domestic Market] details—that’s kinda what I’m doing with it. I like seeing how these cars were back in the day.”

The gullwing owners of the 1950s and 1960s were largely uninterested in keeping their cars true to what the factory had done. Instead, they personalized and accessorized in pursuit of individualized aesthetics and greater speed. Robert has done both, starting with a 300 SL that has been in his family since the mid-1970s, when these cars were shifting from cool transportation and hobby cars to full-blown collectibles.

“If you were a Mercedes nerd circa 1965, and you had followed all the changes…” is how he describes the basic plan that finally came to fruition in March 2023 when the family 300 SL came back to life as a mechanically perfected and period-restyled tribute to that era.

Robert became aware of those custom-rodded gullwings he’s recreating thanks to a metalworking class he took from a famous hot rodder and customizer who has been active since the mid-1940s.

“I took a class from Gene Winfield,” he says. “He’s got a pic of 300 SL in his parking lot in the ’50s.” There are similar photos of custom-painted and otherwise personalized gullwings at the premises of similar figures of the era, like Monkeemobile-creator Dean Jeffries. Largely, though, those cars haven’t survived in their period-modified form, but luckily Robert had access to that not-quite-correct 300 SL as a potential canvas for his own version.

“My grandfather bought it in 1976 from a weird doctor in Las Vegas,” Robert recalls. Nothing is known about its early history, but there are tantalizing hints. It has a later replacement engine block, which might mean nothing, but Robert also says the front suspension was “whipped” in a way that suggests it was perhaps raced in its early days.

At the time it came into the family, Robert’s car had already been refinished to the blue color it wears now, although it was repainted again in the early 1980s at the same time its interior was reupholstered. That paint job has now mellowed, remaining presentable while becoming less stressful than fresh, perfect paint.

“I like how it’s got dents; I like how it’s got chips,” Robert says. Though he admits the chips get touched up immediately. Keeping that paint in service has driven some of the period touches, as well. Notably, the decals on the doors cover the holes where an old set of side mirrors once mounted. Interestingly, there appears to be virtually zero body filler in this 300 SL—while Robert says he’s seen many cars with up to 200 pounds of the stuff ladled on during restoration.

Details like the bronze roadster wheels, black rockers, and plaid interior elements were also inspired by the color scheme, which Robert says was “too blue” for him originally. The roadster wheels he selected because those later (roadsters were produced from 1957 to 1963) pieces, at 5.5 inches, were wider than those that came on the 1954 to 1957 coupes. The bronze color, inspired by Mercedes’ own W196 and W194 race cars, was selected to offset the blue—as were the period-style pinstriping and vintage and period-style waterslide decals.

Similarly, what was a blue-leather interior has been treated to mildly customized instruments, extensive engine turning, a period tool box (with leather straps coming soon), a race-car-style steering wheel and shaft (the popular Nardi aftermarket wheel, Robert says, obscures the instruments too much for his liking), and replica period-accessory clear-plastic knobs (patterned off an original that was already installed in this car on the turn-signal switch) and is now taking on blue-plaid touches—most notably via a headliner supplied by Mercedes-Benz’s own Classic Center, which replicates the original material in the new pattern.

Robert, who operates gullwing repair-and-restoration specialist W198 Werks (W198 is Mercedes’ internal chassis code for the 300 SL), is a huge fan of the Classic Center, both for parts and major restoration work. “If a car like this gets wadded up,” he says, “it’s best to have the manufacturer fix it.” Numerous parts came from the Classic Center as well, including the cylinder head, which sits atop a 1959-vintage service-replacement block. Other modifications to the 3.0L (183-cu.in.) SOHC straight-six engine include upgraded “roadster” oiling, a slight overbore (with a stock-stroke 300 E crankshaft of mid-1960s vintage) and a custom header done by a friend. The header connects to a fabricated exhaust system that incorporates both a stock muffler and a cutout, the latter of which produces the glorious noise that originally brought this car to our attention.

The net effect of the modifications is an engine that produces 270 horsepower at the flywheel—with more to come once the planned installation of a Joe Hunt magneto is completed. Compare that with the 195- to 200-hp stock rating. It’s even more impressive when you learn that all of this is done in a way that allows Robert to use regular pump gas and off-the-shelf motor oil—something he says he tries to do for every engine build he undertakes. No lead is required in the gasoline, thanks to hardened valve seats in the aluminum cylinder head, and the car averages 15 to 17 miles per gallon in regular driving.

That thoughtfully upgraded engine resides in a car that is several hundred pounds lighter than stock, thanks in part to Plexiglas windows. Those came thanks to a customer with a factory aluminum-bodied race car that had somehow been equipped with glass windows. When that customer commissioned a restoration including proper Plexi, Robert had the aircraft company he contracted with produce three sets based on original glass.

The chassis, too, has been upgraded to make the most of its design and complement the increased power. Swing-axle rear suspensions have become notorious in the wake of Ralph Nader’s writing on the early Chevrolet Corvair, but in the ’50s they were considered a viable form of independent rear even for full-bore race cars. Mercedes revised the 300 SL’s swing-axle pivot location during the 1957 switch from gullwing-coupe production to roadsters. One of the ways the company tuned the high-performance behavior of the early, low-pivot swing axle arrangement was with limiting straps to prevent excessive de-camber in hard cornering—something not considered necessary on the initially economy-focused Corvair. Mercedes race teams, meanwhile, sometimes took the factory suspension setup a step further, shortening those straps a full inch or more or even substituting chains to make the limit adjustable. Robert has copied that practice by installing shorter-than-stock limiting straps.

Further chassis improvements include a set of high-speed (3.25:1) differential gears, a power-brake booster from a 300 SL roadster, Koni shocks, new sport springs from Mercedes, gusseted lower spring plates, a “big” front anti-sway bar, and a rear anti-sway bar. None of this is just for bragging rights, either, as this car gets driven far, often, and hard. That Speed Pilot rally computer (a vintage European piece) on the dash is a hint about this 300 SL’s major purpose in life.

“We’re like a custodian,” Robert says of the philosophy that guides him and owners of similar cars put to similar uses. They like speed but their guiding principle is “Go fast, but smart fast.”

This car’s first high-velocity outing in its period-modified form occurred even before it was complete. While it was first mobile in March of 2023, the next month it still lacked side windows and a transmission tunnel when it set out on the Copperstate 1000, a vintage car road rally that each year sees around 80 pre-1974 cars cover 1,000 miles of desert, river-valley, and mountain roads in Arizona and surrounding states. Robert serves as one of the Copperstate’s official mechanics.

Since then, he’s also sent his mother and her cousin off in it for the 300 SL Classic Rally around Lake Tahoe; taken it on the Pebble Beach Motoring Classic from Seattle to Monterey Car Week; driven it cross country (“with an 80-year-old passenger and a carful of luggage”) from Portland, Oregon, to Quebec City, for the Gull Wing Group’s 2023 convention (Robert’s a board member); displayed it at the Grand National Roadster Show; and used it as a rally chaser at a private rally. At the start of the Portland-to-Quebec trip, the car even drove through snow in Oregon—certainly, a rare experience for any 300 SL in the last few decades.

The car also sees extensive local and regional use individually, too. On New Year’s Day 2024, for instance, Robert joined up with some friends in a traditional hot-rod club for a local run celebrating the holiday. He’s also seen very little pushback from purists.

“It’s irreverent, but lot of people appreciate it,” he says. Likely those in the know also appreciate that Robert is paying tribute to an often-overlooked part of the gullwing story. He’s also a worthwhile caretaker, who provides all the appropriate care and feeding due a vintage exotic. “I’ve done 10 oil changes in 10,000 miles,” he notes. That’s necessary due to both the low oil temperatures the engine runs and the nature of its oil-pressure-actuated fuel pump, which causes the mechanical injectors to keep pulsing momentarily after the ignition is off, inevitably resulting in fuel dilution of the oil.

We salute you, Robert, and your hard-driven, period-modified gullwing Mercedes. Keep it up.

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