Mercedes-AMG SL 43 Road Test

Never think of Mercedes-AMG’s new SL 43 as an entry-level car, even if Mercedes-AMG calls it such. Instead, SL 43 is Mercedes-AMG’s simpler rear-wheel drive alternative to the Affalterbach firm’s all-wheel drive V8-powered SL 63. Though they share fundamental architecture, each car offers a unique approach to driving satisfaction—they are performance bookends, not so much entry level and top of the line.

Whereas I consider the SL 63 the finest Gentleman’s Sport-Tourer on the U.S. market, offering supercar power from its twin-turbo V8, the SL 43 is the Jungmeister Roadster, a big step up for a young man who likely cut his teeth from high school to grad school on sport compact cars with turbo 4-cylinder engines. If Mercedes-AMG’s established approach to product planning and marketing holds true, an even hotter version of the SL 43 might arrive later—that’s a car I’d very much enjoy on a mountain run.

Central to SL 43’s performance narrative and lower price point is its simpler rear-wheel drive powertrain that ably exploits the 354 lb.-ft. of torque from its electric-turbocharged 4-cylinder engine. Without the added weight of a drivetrain for the front wheels and with a lighter 4-cylinder engine, SL 43 tips the scales 353 pounds lighter than big brother SL 63, and that changes character dramatically.

Electric turbochargers and tiny electric superchargers have been around since the 1990s but have found limited application. In recent years electric turbos have been proven in Mercedes-AMG’s Formula One mild-hybrid race cars, and the concept has now cascaded to SL.

In function an electric turbocharger blends the easy efficiency of an exhaust-driven turbocharger with the instant-on boost of a mechanical supercharger, but without anywhere near the weight, complexity and demanding mathematics required to power-up a mechanical supercharger.

SL 43’s instant-on boost is not “for free” because the 4-inch electric motor must draw considerable juice from a 48-Volt system through stout electric cabling, and the turbocharger has water jackets to keep it cool, adding weight and complexity. But compared to the inefficiency of mechanical screw-type superchargers, which can require massive amounts of horsepower to spin effectively—horsepower that never reaches the rear wheels—a trickle of electricity to a small electric motor is pretty darn close to “free power.” Cleverness beats brute force might be a theme for SL 43’s engine.

Driven by the electric motor, the turbo instantly forces large amounts of air into the combustion chambers. Think of your girlfriend’s or wife’s wailing hair dryer waking you up in the morning—doesn’t that thought give you a smile? —with its massive airflow bringing volume and style to her lovely hair. This electric turbo is the industrial high-performance version of that, operating on much higher Frankenstein voltage. But you will never hear it, or sense it. When it comes to electric turbochargers, it always pays to be discreet.

Engine sounds and exhaust note are appropriate for a refined Jungmeister roadster. Just because it’s a 4-cylinder doesn’t mean it should sound like a 16-year-old’s sport compact hatchback with an uncorked exhaust pipe. SL 43’s war song is rich and sonorous, growing sharper as revs climb. When ambling along in traffic, sounds are subtle and pleasant. This is no hooligan car—it’s for the man who has graduated beyond the Hooniverse.

The rest of the car offers variations on proven subsystems and components from both Mercedes mainstream and Mercedes-AMG, which means it’s all beautifully rendered.

To save weight and cost, SL 43 rides on conventional springs, not air springs. Damping is excellent, and one can choose from the expected menu of calibrations: Comfort, Sport, Sport+ and then Individual, plus another setting for inclement weather. Metal springs limit how plush Comfort can be, but there’s considerable range, with palpable differences in each setting. AMG did not skimp on the damper design.

As with all such cars I drive over the brutal roads of Los Angeles, it’s best to use an Individual calibration, with suspension set to Comfort and powertrain to Sport or Sport+ to maximize engine response rates. Sport+ suspension settings are very taut, best saved for smooth asphalt roads one explores on a crisp morning as the sun peaks over the ridgetop.

SL 43 uses the AMG-tuned and tweaked version of the Mercedes 9-speed. The top three gears are for highway. Eighth and ninth gears are difficult to hold at speeds less than 85 mph. The transmission’s black box scripting simply wants to kick down to seventh or sixth to keep the engine from bogging. The top two gears are for relaxed long-distance runs on straight highways, saving wear and tear on powertrain and occupants. Think LA to San Francisco, or Jersey to Florida, maybe Seattle to a second home in Idaho.

It’s on the hunt when SL 43 shines. For mountain work, third and fourth gears are best, helping set up a nice flow from corners to straights to braking and back again. At 3,825 pounds, SL 43 is no lightweight, but most of the weight savings came out of the nose, close to the front axle line, allowing SL 43 to change direction with style.

Putting SL into a mountain corner, or even attacking a flying right-hand turn on an urban boulevard is a beautiful experience. SL 43 has shed enough weight, is svelte enough to work with physics rather than conquering physics through suspension geometry and torque vectoring.

SL 43 is no supercar with a sub-3 second sprint to 60 mph—from a stoplight, SL 43 can hit 60 in 4.7 or 4.8 seconds. No 10-second quarter mile times, either. SL 43 can dust off ordinary cars in traffic, sure, especially on the highway. But it thrives on mountain roads working between 25 and 100 mph. But it is as quick or quicker than all but one of the comparable German roadsters. And SL 43 is far prettier and more distinctive, too.

The architecture, interior, and exterior design are all the same fine work found in the SL 63 I had months ago. Gorden Wagener has been Mercedes design boss since 2016 and cars sketched under his management are elegant. The SL is fresh and handsome, entirely 21st Century, yet timeless, clearly evolved from the voluptuous curves of 1950s SLs. Any 2023 SL will look wonderful when grandchildren in 2050 or 2060 are squabbling over who gets to take it home.

As a first major steppingstone to ever greater cars as a career unfolds, SL 43 may prove one to keep long-term. The functional CUVs and sedans, even supercars purchased later will be let go over the course of decades, replaced with others, merely flourishes in the tapestry of an automotive lifetime.

But I suspect many families will choose to keep an SL long-term, including this one. Long-term single-family ownership is a clear pattern with SLs over the past seven decades, proven by the number of single-family SLs that become auction lots at Pebble Beach, Amelia, and Scottsdale.

For the Jungmeister with freshly minted associate status at a tier one law firm, or a well-compensated product development gig in tech, SL 43 is an ideal transition from the hardship cars of grad school, an excellent reward car. Along with that lovely woman who will help renovate your wardrobe, an SL 43 can be a significant step on the way to status as a true gentleman.