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June 16, 2021 12:00 am by

The R129-Generation Mercedes-Benz SL is a Used Car Hidden Gem

1995 Mercedes-Benz SL600 front


The Mercedes-Benz SL-Class traces its roots all the way back to the 300 SL Gullwing, a 1950s style icon that drove even better than it looked, capturing the checkered flag at storied races like Le Man and the Carrera Panamera. These days a Gullwing will set you back a cool million. But there’s another SL out there that’s not only a deserving heir to the name but also a great value: the R129 generation.

Produced from 1990 through 2002, the R129 Mercedes SL wears classic lines that look sharp to this day. Famed designer Bruno Sacco called it his masterpiece. And its beauty isn’t skin deep. Under the hood you’ll find a number of legendary engines, including V8 and V12 mills with their own impressive racing pedigrees.

The supply of nice R129 SLs is quite good, thanks in part to its long production run and also to the fact that many owners kept them as second or third cars, driving them only on special occasions. Now, thanks to the power of depreciation, these excellent roadsters are also about as cheap as they’ll ever be.

So if you’re in the market for a classic roadster that looks like a million bucks but only costs about $10-15 grand, you’re in the right place.

The Best Years

While Mercedes-Benz produced the R129 SL for over a decade (1990-2002), we recommend that you focus your search on the following configurations and model years.

R129 Mercedes-Benz SL500 top down

1996-2002 SL500

Available from the get-go in 1990 was the 500SL, which boasted a 5.0-liter “M119” V8 good for about 320 horsepower — a formidable figure for the day. With dual overhead cams (DOHC) and variable valve timing, it was an exceptionally advanced engine, and its performance remains thrilling decades later. However, the excellent electronic five-speed transmission didn’t arrive until 1996, so we do not recommend earlier models with the workmanlike four-speed hydraulic slushbox (although this transmission is certainly capable of sporting upshifts, as seen here, and it’s worth noting that Porsche borrowed it for the 928).

It’s also important to note that the M119 V8 was phased out in ’99, replaced by the single overhead cam (SOHC) 5.0-liter “M113” V8. This V8 was down a bit on power, dropping from the ’98 SL500’s 315-hp rating to 302, but it delivered more torque at lower engine speeds, giving it a slightly more energetic feel around town, albeit without quite matching the M119’s rousing high-rpm surge.

Some say that ’97 and ’98 were the quote-unquote best years due to the convergence of the M119, the five-speed automatic and some notable interior upgrades, including an updated climate-control interface with a large digital display. But the M113 cars are likely to be in better condition at this point, so try both and see what you think.

1995 Mercedes-Benz SL600 side

1996-2002 SL600

The SL600 employs a 6.0-liter V12 (389 hp) that’s essentially two inline-6 engines put together. The V12 was the only R129 engine that made it to the end of the run without significant modification. Like the SL500, the SL600 had to wait until ’96 to get the electronic five-speed automatic, so we do not recommend earlier years. We particularly like the ’99-’02 range because it’s not saddled with the garish two-tone leather interior found on earlier 600s.

The 600 came standard with a novel adaptive suspension featuring standard and “sport” modes, as well as adjustable-height capability; this setup was optional but very rarely specified on the lesser models. It’s a potential maintenance headache, to be sure, but it’s less complicated than the subsequent Active Body Control suspension, and it perceptibly improves both ride quality and handling composure.

Every 600 boasted standard interior upgrades, including stitched leather paneling on the dashboard, doors and even sun visors, not to mention a very cool “V12” shift knob for a few model years prior to ’99.

SL600 M120 V12 engine

Does this engine deserve its top billing in the R129 lineup? But of course. Silent and all but imperceptible in normal operation, the V12 rips from about 4,000 rpm to redline à la one of the era’s supercars, making for a unique experience that can’t be measured by its scant acceleration advantage alone (figure high-fives to 60 mph, versus low-sixes for the V8 cars). Durability should be on par with the rest of the family, which is to say excellent, but regular service by a mechanic familiar with this unusual engine is an absolute must.

There’s also the simple fact that only 11,000 or so 600s were made in total from ’93 to ’02 — that’s global production, mind you — with no more than about 1,500 of those built for the desired ’99-’02 model years, so it may be prohibitively difficult to find a well-maintained specimen in your price range.

1997 SL320

The six-cylinder SL320 used a 3.2-liter version of Benz’s remarkably durable (if blown-headgasket-prone) “M104” inline-6 engine. As noted, we do not recommend purchasing an R129 with the original hydraulic transmission, and the six-cylinder lineup didn’t get the modern electronically controlled five-speed automatic until 1997 — its final year of U.S. production. The inline-6 is actually plenty powerful in its upper registers, with a surprising snarl near redline.

If you can find a nice ’97, the savings over a comparable 500 or 600 may be too significant to resist.

Problem Areas

If you’re cool with earlier R129s that don’t have the electronic five-speed transmission, be forewarned that the ’93-’95 models — and perhaps some ’92s as well — used biodegradeable wiring-harness insulation that causes all sorts of strange maladies when it inevitably falls apart. The good news is that if the car is running well at this point, it’s probably had its harness replaced, but hopefully this procedure was fully documented by a previous owner.

Another common issue is leaking from one or more of the dozen hydraulic cylinders which are integral to opening and closing the convertible roof. Fortunately, an aftermarket supplier has stepped in here with an excellent rebuild kit. If the job hasn’t already been done, expect to pay about $600 to do it yourself. Be warned: it’s fairly involved, so add another grand or so if you’d prefer to have an independent shop do the labor.

500SL service records

Speaking of documentation, every used car becomes more attractive when accompanied by copious service records, but this factor can really make or break a deal for an old Mercedes. The R129 was designed to last and last if properly maintained, but proper maintenance requires consistent investment over time, and you don’t want an R129 that wasn’t given ongoing TLC. Proceed with caution if records aren’t available, even if the car looks and drives great.

Also, give priority to cars shod with high-quality tires — typically Michelin (bonus points) or Continental. If the previous owner selected substandard tires for a 2-ton-plus, 155-mph German performance car, a corner-cutting philosophy is strongly implied.

Buying Tips

Changes worth noting across the lineup include the arrival of the astonishingly good standard Bose stereo for ’94; the elimination of the original two-tone bodywork for ’96, which also saw the introduction of more modern-looking interior door panels and reshaped seat-upholstery sections (both visible in the ’98 interior photo below); the new climate control unit and an optional “panoramic” glass hardtop for ’97 (replacing the standard and more angular aluminum hardtop when specified); and significant updates for ’99, among them upgraded front brakes with Brembo four-piston calipers, new taillights and mirror housings, slightly revised bodywork, Nappa leather upholstery without perforation and a new stereo head unit.

Mercedes R129 interior

Also of note, an AMG-inspired sport package with subtle body effects (but no suspension changes) became optional in ’97, continuing for ’98 with the same staggered-width “monoblock” 18-inch wheels. Xenon headlights also became optional around this time and are quite desirable today, as the base American headlights are woefully inadequate on dark rural roads. For ’99, the sport package received second-generation AMG wheels with more prominent spokes. That sport package was made standard on all SL models for 2001 and 2002.

Aesthetically, the R129 tends to wear quite well, like other Benzes of this and prior vintages. One exception concerns the horizontal seam that spans the width of the dash (see photo above), starting above the compartment that’s above the center climate vents. With sun/heat exposure over time, the soft upper dash covering will warp upward at that seam. It’s an annoying flaw that’s not present in the contemporaneous W124 E-Class, for example, which had no such seam, although the W140 S-Class is similarly afflicted. If you find an R129 with little or no warping in this location, it has almost certainly been garaged, which in turn indicates a relatively pampered life.

Price Ranges

$30,000+ is the “Wild West” price bracket where you’ll find either a jaw-droppingly amazing R129 in a very desirable configuration that has hardly been driven. A handful have even closed over $40,000 on Bring a Trailer in the last year, so there is a market for these in museum-like condition. But you don’t need to pay that much.

$20,000-$30,000 still buys you one of the best examples in the world (top 2%) with very low miles, or a highly collectible variant in excellent condition (probably a Silver Arrow).

$16,000-$20,000 affords you an outstanding example with less than 50k miles (top 10%).

$11,000-$16,000 gets you a nicely-preserved car with 50-80k miles or a higher-mileage car that’s been astonishingly well-maintained (top 25%).

For $7,000-$11,000 you can find a reasonably clean car with “good bones” that may have higher miles and/or a few issues that can relatively easily be addressed (top 50%).

Finally, $7000 and under buys you an average-at-best car that has higher miles and a number of notable flaws (bottom 50%).

1995 Mercedes-Benz SL600 rear top down

The Bottom Line

It bears repeating that a pre-purchase inspection is a no-brainer on any R129 you’re considering. The fully automated convertible top mechanism must be tested by a knowledgeable technician, and the same goes for the rest of the complicated systems in this complicated car.

The good news is that despite that complexity, R129s are known to reach high mileage with ease, provided they’ve been well cared-for by previous owners. It’s a great time to get in on the action with these future classics.

Photos courtesy of Mercedes-Benz Classic Center and the author


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