Seven decades of open-top automotive royalty
The Mercedes-Benz SL is an iconic luxury grand tourer that has been in continuous production since 1954, sitting at the top of Mercedes' convertible range. It competes with the Porsche 911 Cabriolet, Jaguar F-Type and BMW 8 Series Convertible, appealing to well-heeled buyers who want effortless performance with open-top refinement. It holds strong classic car appeal across multiple generations, particularly the R107 and R129.
We track 5 known issues across the Mercedes-Benz SL range, including 2 rated as safety-critical. Knowing which variants and configurations to approach with caution can save you from expensive surprises after purchase.
Found a Mercedes-Benz SL? Enter the reg to see which of our 5 known issues apply to that exact car, plus full MOT history and mileage checks.
R107 (1971–1989) — Engine options included the 2.7 V6, 2.8 V6, 3.8 V8, 5.0 V8.
R129 (1989–2001) — Engine options included the SL280, SL300, SL320, SL500, SL55 AMG. Our database flags 4 known issues on this generation, 1 of which are rated as safety-critical. The most significant concern is Flexible brake hose deterioration (£200–£400 to address).
R230 (2001–2012) — Engine options included the SL350, SL370, SL463, SL500, SL55 AMG, SL55 Black Series, SL65 AMG. Our database flags 4 known issues on this generation, 2 of which are rated as safety-critical. The most significant concern is Flexible brake hose deterioration (£200–£400 to address).
R231 (2012–2020) — Engine options included the SL300, SL350, SL450, SL500, SL550.
Flexible brake hoses on SL models deteriorate at 24.3 times the national fleet average, with failures documented across all mileage ranges from 20,000 miles upward. The flexible sections connecting the brake calipers to the rigid brake lines are subject to heat cycling from the brakes and movement from suspension travel. Age-related rubber degradation causes internal delamination and external cracking, potentially leading to brake fluid loss and brake failure. This is classified as dangerous due to the direct safety implications.
Complete brake hose failure results in immediate loss of braking on the affected wheel and potential loss of pedal pressure if multiple hoses fail. Even partial deterioration affects braking balance and pedal feel. The car should not be driven if brake hose failure is suspected. Complete brake hose replacement typically costs £300-£600.
Check brake disc condition for lipping or scoring. Test braking at moderate speed for pulling to one side or vibration through the steering wheel. Review MOT advisories for brake-related items.
This typically manifests as corrosion to the rear subframe mounting points, front suspension mounting areas, and sill structures that support the convertible top mechanism. The aluminium-steel construction creates galvanic corrosion issues where dissimilar metals meet. Once structural rigidity is compromised, the convertible body experiences increased flex which accelerates further deterioration and affects occupant safety in a collision.
Structural corrosion compromises crash protection and can make the vehicle unsafe to drive. Advanced corrosion may render the car uneconomical to repair. Professional structural assessment and repair can cost £3,000-£8,000 depending on the extent of damage. Severely corroded vehicles may fail MOT testing on safety grounds.
Inspect the wheel arches, sills, jacking points and door bottoms carefully. Press gently on sills to check for soft spots. Look underneath for corrosion on structural components. Check the MOT history for corrosion-related advisories or failures.
The recirculating ball steering box on R129 5.0-litre models develops internal seal failure, allowing power steering fluid to leak from the box housing onto the road surface. The steering box is a sealed unit requiring complete replacement rather than rebuild, making this an expensive repair. Later R230 models use rack-and-pinion steering which is not subject to this specific failure mode.
Complete loss of power steering assistance makes the car extremely difficult to control at low speeds and dangerous in emergency situations. Continued driving with a leaking steering box will damage the power steering pump due to low fluid levels. Total repair cost including steering box replacement ranges from £1,200-£2,000.
During the test drive, check the steering for excessive play, vibration or pulling to one side. Listen for groaning or whining when turning the wheel at low speed. Power steering fluid level and condition should be checked on hydraulic systems.
The rubber dust covers protecting ball joints and suspension bushes deteriorate rapidly on SL models, failing at 52 times the national fleet average according to MOT data. Once the protective cover splits, dirt and moisture enter the joint causing accelerated wear and eventual failure. This affects multiple suspension components simultaneously across front and rear suspension systems. The combination of age-related rubber degradation and the convertible body structure's increased chassis flex accelerates this deterioration.
Failed dust covers lead to rapid deterioration of expensive suspension components. A complete front suspension overhaul including ball joints, bushes, and track rod ends typically costs £2,000-£4,000. Severely worn suspension compromises vehicle stability and braking performance.
Listen for knocking, clunking or rattling over bumps during the test drive. Inspect the underside for corroded or cracked suspension components. Check the MOT history for suspension-related advisories, which often predict future failures.
Wheel bearings on SL models fail at 21.7 times the national fleet average, with peak failure rates on 2.8-litre variants in the 40,000-60,000 mile range. The combination of the car's weight, performance driving patterns, and age-related seal deterioration leads to premature bearing wear. Front bearings typically fail first due to steering loads and braking forces. A failed wheel bearing creates dangerous handling characteristics and can lead to wheel detachment if ignored.
A completely failed wheel bearing can cause the wheel to detach from the vehicle, creating extreme danger to occupants and other road users. Even partially worn bearings affect braking efficiency and steering precision. Individual bearing replacement costs £200-£500 per corner.
Listen for knocking, clunking or rattling over bumps during the test drive. Inspect the underside for corroded or cracked suspension components. Check the MOT history for suspension-related advisories, which often predict future failures.
For the full breakdown of all 5 tracked issues with repair costs, see the Mercedes-Benz SL common problems page.
Based on 125k real DVSA MOT tests, the Mercedes-Benz SL fails more often than average on several items. The biggest outlier is light unit fault at 155x the fleet average, followed by steering rack wear (152x).
When viewing a specific car, check its MOT history for recurring advisories in these categories. See the full Mercedes-Benz SL MOT failure breakdown for data at every mileage point.
Routine servicing (oil and filter change every 10k miles) typically costs £120–£200 at an independent garage.
The bigger-ticket items to budget for include spark plugs (£200–£400).
See the full Mercedes-Benz SL service schedule for every interval and cost breakdown.
The Mercedes-Benz SL has some well-documented weak points, including 2 safety-critical issues that demand careful checking. The right example, properly maintained, can still be a sound purchase — but cutting corners on the pre-purchase inspection is not advisable. 2013-2020 R231 generation offers the best balance of modern tech, reliability and retractable hardtop. The 2017-2020 SL450/SL550 facelift is the sweet spot with updated infotainment and fewer teething issues. For classics, the 2004+ R230 facelift fixed many early electrical issues. Avoid 2001-2003 R230s.
Before committing, check the car's full MOT history, verify the service record is complete, and if possible arrange a specialist inspection. Enter any registration into our free report to see the complete picture.
Get Car Wise maintains a database of known mechanical issues for every popular car on UK roads, tracking the faults that owners, specialists and DVSA data reveal.
When you run a report on a specific Mercedes-Benz SL, we cross-reference the exact variant, engine and age against our database of 5 known issues. Combined with full MOT history analysis, mileage verification and DVLA data, you get a complete picture before viewing.
Enter the registration for MOT history, mileage verification, known faults for that exact variant, and a Get Car Wise Score.
This guide was compiled from independent expert reviews, DVSA MOT data, specialist workshops and our own database of 5 known Mercedes-Benz SL issues. We are not affiliated with any source listed.