As Merc’s most highly developed mainstream two-seater roadster, the SL has never been a car for the masses, but some editions are rather more affordable than others.
Ever since the legendary Gullwing of 1954, the Mercedes SL has represented one of the most thoroughly engineered two-seaters on the market. Aside from the Gullwing, all those SLs have been two-seater roadsters and they’ve all offered effortless performance with understated style.
While the 300SL and the Pagoda that succeeded it now fetch big money, the R107 that arrived in 1971 is more affordable – but values for those are rising fast. Which leaves the R107’s successor as the most affordable SL of all. Known as the R129 and launched in 1989, this fourth-generation SL was initially offered in 300SL-24 and 500SL forms. It was an immediate hit and in 1992 Mercedes took the SL even further upmarket with the launch of a 6.0-litre V12 option in the 600SL. In 1993 the 3.0-litre engine was ditched in favour of 2.8 and 3.2-litre straight-six options in the 280SL and 320SL respectively. This was also the year in which the SL switched from being a suffix to a prefix; the 500SL became an SL500.
In 1998, more efficient V6 engines replaced the previous straight-six units, still with 2.8 and 3.2-litre displacements, but there was more power with improved fuel economy. There was also a new engine for the SL500 (the 4966cc M113 replaced the 4973 M119 unit). For those who wanted serious power though, it was in 1995 that the ultimate R129 arrived; the SL73 AMG. Powered by the same 7.3-litre V12 that would later see service in the Pagani Zonda, this 525bhp monster was the most powerful production SL ever – just 85 were built. Within a year there was also an SL60 AMG, with a 376bhp 6.0-litre V8.
So whether you want a tyre-shredding supercar or a more demure relatively frugal cruiser, there’s an R129 for you. Most editions are eminently affordable – although SLs always go up in value eventually. Some R129s are already appreciating, so if you buy well, you could enjoy some seriously cheap open-topped motoring.
VITAL STATISTICS
SL500 M113
Engine 4966cc/8-cyl/4OHC
Power (bhp@rpm) 306@5600
Torque (lb ft@rpm) 339@2700
Top speed 155mph (limited)
0-60mph 6.2sec
Consumption 20mpg
Gearbox 4/5-speed auto
WHAT TO LOOK FOR
BODYWORK
Thanks to excellent rustproofing and high-quality paint, there’s no reason for an R129’s bodywork to look tatty. You can even keep these cars outside in the winter, so the R129 really is a year-round sportscar. However, the bonnet and radiator grille are prone to stone chips so it may be that a respray of the nose is needed every few years.
ENGINE
R129 engines are incredibly durable if maintained, but oil leaks are common. The unstressed M113 and M119 V8s fitted to the SL500 are particularly long-lived. The M103 and M104 straight-sixes (fitted to the 300SL, SL280 and SL320) can suffer head gasket failure at about 100k miles. Early cars are suffering from wiring loom problems leading to misfiring; budget £1000 to fix a head gasket and £1500 to replace the loom. The M120 V12 in the SL600 is a superb engine, but fuel and maintenance costs are steep, while the dynamics are spoiled by the extra weight. It also doesn’t offer any extra usable performance over the SL500.
RUNNING GEAR
Only a few six-cylinder SLs got a manual gearbox; the great majority of SLs are autos. The electronically controlled five-speed transmission fitted from 1996 is much better than the hydraulically actuated four-speeder previously fitted. All transmissons are strong, but hard-driven cars can suffer from a worn back axle, so listen for whining. The steering, suspension and brakes are also tough, but repairs can be costly on SLs fitted with ADS (the adaptive damping system). Optional on all R129s apart from the SL600 (on which it was standard), ADS was rarely specified because of the high cost when new (around £4000). If it plays up, repairs are costly; if fitted the car should have an amazingly smooth ride which is why it’s worth having.
TRIM
The electrically folding soft top can play up, so check that it raises and stows smoothly; jump starting can damage the control module. Look for evidence of hydraulic leaks by the sun visors and around the rams in the boot. Gremlins can be hard to eradicate. The plastic windows in the soft top crack with age – and check the quality of the roof in general as some replacement hoods are poorly made.
An aluminium hard top was standard, and from 1993 a wind deflector too. Check the hard top for corrosion, especially at the base of each pillar. The best hard top is one of the panoramic items offered from 1995, as these really light up the cabin. With a smoked glass panel that covers the entire roof, it’s superb but much heavier than the standard roof. The seal arrangement was changed in 1995, so hard tops made after this date won’t fit earlier cars, and vice versa.
Be wary of modified cars, as ‘improvements’ are generally undesirable. Watch out for aftermarket wheels, stereos and exhaust systems and make sure the tyres are decent; any owner who fits cheap rubber has probably skimped elsewhere with their maintenance. Wheels increased in diameter from 16 to 17 inches in June 1998, to clear the upgraded brakes fitted from that point. Autocar reckoned these were the best brakes fitted to any production car in the world at that time, so upgrades really are unnecessary.
ELECTRICS
The electrics can be problematic with effective repairs potentially very expensive. A failed xenon light typically costs £500-£1000 to fix while the bill to repair a seized wiper motor might be £700. Also check that the air conditioning works properly; failed condensers aren’t unusual and these can easily cost well over £1000 to put right. Later cars got more standard equipment but Mercedes had reduced the quality of the interior materials by this point, to cut costs.
VERDICT
More of a cruiser than a sportscar, the Mercedes SL is a true performance car bargain as it’s beautifully built and utterly usable. But when an R129 goes wrong it can cost plenty to fix, so while we’d recommend the Merc wholeheartedly, make sure you do your homework before buying.
AUTOMATIC 
RHD
