The mirror-like deep-maroon finish setting off the rich, Cognac leather interior of a classic Mercedes-Benz sedan arrests the eye from across the sunlit show field. Closer inspection reveals trunk-lid badges marking the big four-door as a rare 300SEL 6.3. A glimpse of a massive engine under the hood confirms that this is one of the astoundingly fast but visually understated executive-express automobiles built by Mercedes-Benz from 1968 through 1972.

However, the stunning quality of the restoration and the rarity of the car aren’t the only unusual features. According to the restorer standing nearby, this is, in fact, the very 6.3 bought by Graham Nash in 1970 when folk-rock group Crosby, Stills & Nash was at the top of the charts; the 300SEL is now restored to exactly the condition in which he bought it.

The glorious 6.3 in the sunlight.

The 300SEL 6.3

The idea of swapping a powerful engine into a standard passenger car was not a new one in the 1960s – Jaguar had for many years touted the fact that its luxury Jaguar Mk II sedan with a 3.8-liter E-Type sports-car engine was the fastest production automobile on the road.

So in 1966, it wasn’t a giant conceptual leap for Mercedes-Benz engineer Erich Waxenberger to insert the M100 6.3-liter, V-8 engine designed for bespoke 600 limousines into the long-wheelbase version of the staid W109 luxury sedan. When chief design engineer Rudolf Uhlenhaut first drove the car, he was reportedly amazed not by its performance, but by the fact that the huge engine could really fit under the hood of the 300SEL. 

The hybrid machine offered serious performance. The big engine delivered 300 SAE horsepower and an amazing 434 pound-feet wall of torque, rocketing the nearly two-ton car from zero to 62 mph in 6.6 seconds. Top speed was a stratospheric 137 mph. The 300SEL 6.3 would even spawn a new direction for Mercedes-Benz Cars: Soon, a small independent tuning company run by Hans Werner Aufrecht and Erhard Melcher in Affalterbach would bore out the engine even further, and then run a W109 dubbed the “Red Sow” to notable victories as AMG’s first racecar.

Given that high-powered executives were the target market for the 6.3, the car’s rated fuel efficiency of a paltry 15 miles per gallon didn’t much matter, especially with gasoline selling for as low as 30 cents per gallon during the 1967 price wars.

Befitting the position of the new machine at the summit of Mercedes-Benz’s mainstream model lineup, the 6.3 was fitted as standard with power steering, self-leveling air suspension and four-wheel-ventilated disc brakes, as well as a pneumatic central-locking system adapted from the 600. In addition, air conditioning, a power sunroof, rear-seat writing tables, window curtains, audio tape deck and rear reading lamps were available as optional equipment. During five years of production, 6,526 of these incredible vehicles were produced.

This 6.3 and its story

No wonder that by 2014, professional car restorer Dom Mari had resolved to find a 6.3 to return to glory. Mari had been involved with automobiles his entire life – a grandfather managed sales at a Ford dealer and his father worked as a mechanic. When Mari saw the new 1957 Ford Thunderbird at the age of 10, he knew that cars were his destiny. That same year, he talked his way into helping with odd jobs at the Ford auto body shop around the corner from home. “I grew up watching and learning the way it was done in those days, and had a true passion for the process,’’ Mari recalled. “By my late teens, I knew the direction I was going in.”

After working in several shops by his late 20s, Mari realized he couldn’t attain his desire for perfection while working in a commercial body shop; he launched his own restoration business. He described his approach: “These days, everything is high-tech, but in my world, I transform these cars into showpieces with old-world techniques. For 50 years I’ve used the same methods. In the old days, the fancy equipment and the technology of today did not exist. So yes, I’m the old guard who spends hours and hours on one area, who uses air tools when I have to, but I also use my hands to sand and smooth and create the finishes I’ve become known for. My paint work is my calling card.”

Mari’s award-winning restorations have graced the lawn at Pebble Beach. One is housed at the Gateway Colorado Auto Museum and he received a Senior AACA Hershey Award for his 1971 Jaguar E-Type Roadster, among many other accolades.

More recently, Mari has been hooked on Mercedes-Benz, with a focus on 450, 280 and 560 SLs. However, lurking in the back of his mind was a burning desire to apply his talents to a 300SEL 6.3. He got the word out to friends, searched each issue of Hemmings Motor News, and chased down every lead – with no luck.

When he finally started scanning Craigslist, Mari’s luck improved. One evening, an ad for a 6.3 popped up from a reseller in Texas. The owner had acquired it in a collection of 15 cars, but didn’t want to tackle restoring the 6.3 due to the time and expense involved. Within days, Mari had made a deal and the rare old sedan was on its way to his shop in Bucks County, Pennsylvania.

But what, exactly, had he purchased? Mari was just finishing up restorations on a client’s car and his own 1989 560SL; after completion, he showed his roadster at a few shows – taking trophies every time – and in early 2015 was finally able to clear out his shop to focus on the 6.3. As he took the 300SEL apart and began stripping off the maroon paint, his initial assessment of what the car needed was simple: “It needed everything.” He carefully retained a patch of original paint in a protected area of the right rear doorsill so that when it came time to paint the car, he could match the original color exactly.

Mari dug into the 6.3’s provenance. The seller had mentioned that he’d heard the car was once owned by a rock star, but knew nothing more. Using the 6.3’s vehicle identification number, Mari obtained a Mercedes-Benz production certificate, which referenced the dealer to which the new car had been shipped.

Interestingly, the name of the original selling dealer intersected with one of the fables that 6.3 owners tell each other about how it was that Graham Nash and David Crosby, having become successful with rock group Crosby, Stills & Nash, decided to treat themselves to the status and luxury of Mercedes-Benz automobiles.

As retold in Nash’s autobiography, “Wild Tales, A Rock And Roll Life” (Crown Archetype, New York, 2013), in 1970 he and Crosby went to a Mercedes-Benz dealership to buy new cars. Probably because they appeared to be hippies, a wary salesman reluctantly approached, saying he did not think the exclusive sedans were for them. In response, Nash replied, “Mr. Crosby will take the blue one, and I’ll take the maroon one.” Further research confirmed that the maroon 6.3 in Mari’s shop was the car that Nash had driven away in on that long-ago day.

The restoration

Knowing as he did that a mechanically faultless engine is key to a successful 6.3 restoration, Mari had the fuel tank refurbished, changed the engine oil, replaced filters, cleaned fuel lines, and reinstalled the fuel tank with a new fuel pump. Only then did he start the car for the first time: It sprang to life and ran well, with good compression in all cylinders.

Mari then pulled out the power train, suspension and interior, and completely dissembled the car. Next, he mounted the stripped chassis on a rotisserie rig. Mari inspected every inch of the chassis and body, lovingly removing all imperfections, even minor blemishes left from the factory. Bodywork and painting would extend over the course of three years, broken up by work on the 6.3’s mechanical and cosmetic components.

 Having earlier confirmed that the big sedan’s engine was mechanically sound, Mari disassembled the M100 V-8; all components were degreased, cleaned and serviced, and all gaskets and hoses replaced. He was pleased to find that the head and cylinders were as clean as a whistle, with absolutely no sludge, attesting to both low mileage and careful maintenance. A comprehensive engine rebuild would not be necessary.

The complicated air suspension on a 6.3 is a critical part of the vehicle’s overall performance and appeal. To bring it back to original specifications, Mari replaced all three suspension valves, four rubber bellows and all worn suspension parts.

Mari usually restores a car’s interior wood himself, but in this case – with several pieces broken or missing – he worked with a specialist in California over a six-month period to reproduce the wood trim to his satisfaction. Interior leather was sourced from a specialty supplier in California to match the original door panels, which were in great shape. Mari then reupholstered the seats and cut and installed the carpeting himself. The pristine interior now speaks for itself.

Today, the 300SEL 6.3 is exactly as it was when Nash purchased it in 1970, with one exception. Mari swapped in 15-inch ATS Bundt-style wheels for the original 14-inch stock parts, a substitution typical of the period.

With the restoration completed to Mari’s personal standards, he debuted the 300SEL 6.3 at the 2018 Antique Automobile Club of America’s Annual Grand National Meet, where it was awarded a prestigious AACA national first prize, now proudly mounted on the car’s dignified grille.

The woeful 300SEL 6.3 awaits its resurrection.

Every detail of the 300SEL 6.3 has been skillfully brought back to life.

The star of the show.

Restorer Dom Mari completely overhauled the big sedan’s W100 V-8 engine.

The lustrous Cognac leather interior is framed by contrasting deep-maroon paint.

The best seat in the house.

What comes next? It would be difficult to part with the 300SEL 6.3, but, Mari is in the automotive-restoration business, after all. If another rock star were willing to pay the right price, his resolve might weaken. One thing is certain, however: This beautiful 300SEL 6.3 will never again be a “Long Time Gone.” Meanwhile, club members in need of an expert to restore an R107, W108 or W109 – Dom Mari’s specialties – might want to contact him through the MBCA website.

Dom and Diane Mari

Model testing on the Mercedes-Benz factory test track, Untertürkheim, 1960s.

SPECIFICATIONS

Mercedes-Benz 300SEL 6.3 Sedan (W109)

TYPE: Four-door, five-passenger luxury sedan

ENGINE: M100 6,332, Bosch fuel injection, overhead-cam V-8

TRANSMISSION: 4-speed automatic with center console selector

HORSEPOWER: 300 SAE at 4,000 rpm • TORQUE: 434 lb-ft at 3,000 rpm

LENGTH: 192.9 in • CURB WEIGHT: 3,891 lb

FUEL EFFICIENCY: 15 mpg rated, 11 mpg observed

PERFORMANCE: Zero-60 mph 6.6 sec

TOP SPEED: 137 mph