Hardtop roadster built for cruising, not carving
The Mercedes-Benz SLC (2016-2020) is the final evolution of the long-running SLK roadster line, offering a retractable hardtop two-seater positioned below the SL. It targets buyers who want open-top Mercedes prestige with year-round usability, competing against the BMW Z4, Audi TT Roadster, and Porsche Boxster. It suits comfortable cruisers more than hardcore driving enthusiasts.
We track 5 known issues across the Mercedes-Benz SLC range, with 1 classified as significant. Knowing which variants and configurations to approach with caution can save you from expensive surprises after purchase.
Found a Mercedes-Benz SLC? Enter the reg to see which of our 5 known issues apply to that exact car, plus full MOT history and mileage checks.
R172 (2016–2020) — Petrol options included the SLC 180, SLC 200/250, SLC 300, with SLC 220d on the diesel side. We track 5 known issues on this generation, with 1 classified as significant. The most significant concern is Front wheel bearing premature failure (£350–£500 to address).
Front wheel bearings on the SLC fail at significantly higher rates than the Mercedes fleet average, particularly on 1.6-litre petrol variants. The sealed bearing units develop excessive play and noise much earlier than expected, typically between 20,000-60,000 miles. This is likely related to the SLC's sporting suspension geometry placing higher loads on the bearings during cornering. Failure progresses from rumbling noise to wheel wobble and eventual bearing collapse.
Progressive bearing failure causes wheel wobble, steering instability and potential wheel detachment in extreme cases. The car remains driveable with early-stage bearing noise but should not be driven once play is detected. Replacement requires hub removal and specialist bearing press tools.
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.
Ball joint and tie rod end dust covers (boots) deteriorate prematurely on the SLC, particularly affecting the 2.0-litre petrol and 2.1-litre diesel variants. The rubber boots split or perish, allowing dirt and water ingress to the joint grease. This is an MOT failure point and leads to accelerated joint wear if not addressed. The problem appears related to the SLC's lower ride height exposing components to more road debris.
Split dust covers allow joint contamination leading to premature wear and eventual joint failure. While not immediately dangerous, this progresses to expensive suspension component replacement if ignored. MOT failure requires immediate attention.
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.
The 2.1-litre diesel SLC experiences engine management light illumination at higher rates than typical for Mercedes models. This typically indicates emissions system faults, particularly NOx sensor failure or DPF regeneration issues. The complex emissions system on these Euro 6 diesel engines is sensitive to driving patterns and fuel quality. Short journey patterns prevent proper DPF regeneration cycles.
Persistent engine management lights indicate emissions system faults that will cause MOT failure. DPF regeneration issues can lead to expensive particulate filter replacement. The vehicle remains driveable but may enter reduced power mode if faults worsen.
Check all electrical functions systematically: windows, mirrors, lights, infotainment, heated seats, air conditioning. Look for any warning lights on the dashboard. A diagnostic scan before purchase can reveal stored fault codes.
The 2.0-litre petrol SLC shows elevated lambda (oxygen) sensor failure rates, particularly affecting newer vehicles under 40,000 miles. The sensors monitor exhaust gas composition for emissions control and fuel mixture adjustment. Premature failure may be related to fuel quality sensitivity or the turbocharged engine's operating conditions. Failed sensors cause emissions test failure and increased fuel consumption.
Failed lambda sensors cause MOT emissions test failure and increased fuel consumption. The engine runs in open-loop mode with predetermined fuel maps, reducing efficiency and potentially causing catalytic converter damage over time through incorrect mixture control.
Check all electrical functions systematically: windows, mirrors, lights, infotainment, heated seats, air conditioning. Look for any warning lights on the dashboard. A diagnostic scan before purchase can reveal stored fault codes.
The 2.0-litre petrol SLC shows elevated brake disc wear rates compared to the Mercedes fleet average, particularly affecting vehicles over 40,000 miles. The sporting suspension setup and relatively aggressive brake pad compounds contribute to faster disc wear. Front discs typically show scoring or significant wear patterns earlier than expected, though the trend appears to be improving on later production vehicles.
Excessively worn brake discs cause reduced braking efficiency, steering wheel vibration, and MOT failure. Severely worn discs can cause brake pad backing plates to contact the disc surface, requiring replacement of both discs and pads simultaneously at higher cost.
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.
For the full breakdown of all 5 tracked issues with repair costs, see the Mercedes-Benz SLC common problems page.
Based on 48k real DVSA MOT tests, the Mercedes-Benz SLC fails more often than average on several items. The biggest outlier is any fracture or welding defect on a wheel at 17x the fleet average, followed by wheel bearings worn (16x).
When viewing a specific car, check its MOT history for recurring advisories in these categories. See the full Mercedes-Benz SLC MOT failure breakdown for data at every mileage point.
Routine servicing (oil and filter change every 16k miles) typically costs £150–£250 at an independent garage.
See the full Mercedes-Benz SLC service schedule for every interval and cost breakdown.
The Mercedes-Benz SLC is a reasonable used buy provided you check for the issues outlined above. None of the problems we track are insurmountable, but they do reward buyers who inspect thoroughly and verify the service history before committing. 2017-2018 Sport trim with 17-inch wheels offers the best ride comfort versus the harsh AMG Line. The AMG SLC 43 is the pick if performance matters — the 2019 model gained an extra 23bhp to 385bhp. Avoid AMG Line and Final Edition models unless you accept the significantly stiffer ride from lowered sports suspension and 18-inch wheels.
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 SLC, 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 SLC issues. We are not affiliated with any source listed.