In the past seven years, the roadster exudes a sporty and elegant atmosphere, and the new generation has added modern driving technology.

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Under the long hood is a complex and powerful engine. The cabin is suitable for two adults. The tapered suitcase is large enough to hold golf clubs or gear for a long weekend in Monaco or Montecito. The convertible roof completes the packaging.

This formula can be traced back to the Mercedes SL in 1954, which is a two-door sports car and the longest running nameplate in the history of Mercedes-Benz production cars. (The first letter stands for super leicht or super-light, which is the highest level of sportiness in German.)

Mercedes recently launched a brand new SL, the seventh generation of the model, faithful to its roots, but with major modern updates.

"At Mercedes, the SL is almost the biggest logo we can get," said Gorden Wagener, the global chief design officer of Daimler, the parent company of Mercedes-Benz. "Next to the S-Class, it is the core of the brand — maybe even stronger than the S-Class," he said, referring to the brand's benchmark luxury sedan.

This new SL is the first model to include all-wheel drive and four-wheel steering, enhancing stability, performance and maneuverability. It was the first to be developed from the ground up by Mercedes’ fast subsidiary AMG, which helped design the chassis and will provide a twin-turbocharged 4.0-liter V-8 when it is launched in the United States, with an output of 480 horsepower (in SL 55) or 560 horsepower (in SL 63). It is estimated that the starting price of the SL 55 is only about 6 digits, and the price of additional horses should be about 20% higher.

The new generation is also the first model to promise a plug-in hybrid option, which will be launched later in the product cycle and is based on Mercedes-Benz’s Formula One racing technology, which prioritizes performance over efficiency. It is the first in decades to use an electric folding fabric top instead of a retractable hard top that takes up space. This makes room for another long-lost SL function, a two-plus-two seating configuration with a small rear bucket suitable for accessories such as hand luggage or children.

Many of these elements are designed to help SL restore its former glory. "I am a big fan of the 300 SL Gullwing," Mr. Wagener said, referring to the first model in the series, a hardcore sports car derived from a winning car. "For the new car, I want to make it as close as possible to the first car and try to inject this DNA into the new car."

In addition to reflecting the past, Mercedes also emphasized its vision for the future-"Let it become a very modern SL, a digital sports car, a car that represents the industry undergoing transformation," Mr. Wagner added.

This means that the new SL is full of cutting-edge technology. It has an LCD instrument panel and a nearly 12-inch flat-panel center touch screen. When the top is down and there is sufficient light, it can be tilted and adjusted for better viewing. It has an augmented reality navigation system that can project directional animation onto the windshield in the driver's field of view. Its braking system uses cameras and sensors to detect oncoming vehicles while turning. It can even change lanes and stop by itself (when instructed by the driver).

Mr. Wagener hopes that this artifact can bring fresh fans to the SL crowd. "SL has a very mature customer base, but I think through the new model, we will get many new customers, as well as younger customers," he said.

This injection seems to be necessary. SL has long been a shorthand for the pinnacle of some kind of success - including Clark Gable, Sophia Rowland, Audrey Hepburn, John Lennon, Burt Reynolds, Bob Marley, Tina Te Stars including Na, Jennifer Aniston and Jude Law all have SL. But as the taste of luxury consumers shifted from sporty coupes (and all other types of vehicles) to sport utility vehicles, SL sales fell sharply. In 2003, Mercedes sold more than 13,000 SLs in the United States. Last year, it sold approximately 1,300 vehicles.

The changing product mix may provide some help. The new SL platform will also be used to support the next generation of Mercedes' more serious sports cars, the AMG GT coupe and roadsters. The brand will cancel the two-door version of its S-class sedan, and Mr. Wagner hopes that this move will push "many customers who previously drove S-Coupe and Cabriolet into the SL."

Fortunately, flexibility and adaptability are one of SL's many qualities. Brian Rabold, vice president of Hagerty Automotive Intelligence, is a collector's auto insurance company and a standard for its valuation.

The W198 "Gullwing" SL from 1954-63 was a futuristic outlier, just like an artificial satellite. After the humiliation of cooperation between Mercedes and the Nazi regime during World War II, Mercedes worked hard to regain its reputation. (The 1955-63 model is smaller, similar in style but much less innovative, the W121 is a bit like the stepson of this generation.)

The W113 "Pagoda" SL from 1963-71 is an exquisite mid-century modern building. Its sleek and plain sides and ingenious decorative concave roof earned it its nickname. The R107 "Panzer" SL from 1971-89 was "Me Decade/Greed Is Good", a testament to the dull, chrome-plated personal luxury, forward-looking but baroque anchored in tradition. The R129 SL from 1989 to 2001 is sharp and technically superb, and can be called the glorious end of the analog era.

The R230 of 2001-11 is somewhat amorphous in appearance. Due to the need for a large number of real and virtual buttons to run a cumbersome dashboard infotainment system, and an overly complex foldable hardtop, it was inspired by the possibility of digital design before it could catch up. The 2011-20 R231s are fast and comfortable, but have awkward proportions that are not perfectly aligned; even Mr. Wagner called them "not very attractive."

According to Mr. Rabold, many of these cars are collectible. The high-quality first-generation SL has long been a seven-figure blue chip model. Second-generation cars have appreciated significantly in the past five years, with a 20% increase in value, with outstanding examples reaching six figures. The first-class third-generation cars, especially the 560SL that has ended operation, are also approaching this level, with prices rising by 47% last year alone. Even for fifth-generation cars, interest and value are increasing because they have reached the 20-year historical mark and have begun to transition from used cars to collectibles.

But it is the fourth generation that has experienced the most significant growth. According to Mr. Rabold, since 2016, the value of top V-12-powered models has increased by more than 150%, and the price of even more regular V-8 models has increased even more. More than 75%. Part of the reason for this surge is their elegant design and sturdy engineering, but mainly the generational whims of the collector's car market. Every group is chasing and buying young people's cars. With Gen X's peak income period, cars in the 1990s were very popular.

Mercedes has launched some past stars on the nameplate to add luster to the new SL. This has further stimulated interest in cars that people may have forgotten.

"It always brings the old style back to the spotlight, especially in brands like this and nameplates like this. It draws on such a long history," Mr. Labould said. However, he warned that “an increase in interest does not always mean an increase in the U.S. dollar.”

Although this broad tradition adds prestige and visibility to the latest models, it can also bring tremendous pressure.

"Being the next SL is always a big responsibility," Mr. Wagner said. "You don't want to be the one who screwed up SL."