Used car guide · 1990–2021

Mercedes-Benz SL common problems and MOT failures

What goes wrong on a used Mercedes-Benz SL, year by year: known faults from UK buying guides, the parts flagged at MOT more than on other cars (from 59,749 MOTs done during 2023–2025), and what to check before you buy one.

The 2021 Mercedes-Benz SL

Too few Mercedes-Benz SL cars first registered in 2021 had an MOT during 2025 for reliable MOT figures. There are no known faults on record for this year in the UK buying guides we use, so the rest of this page covers the Mercedes-Benz SL as a whole.

30on the UK register at the end of 2025
Petrolfuel type
What to check on a 2021 car
  • MOT history

    Check the reg below: its MOT history shows what has been failed or advised, and whether the mileage adds up.

  • Service history

    Look for regular servicing and receipts for big jobs like a cambelt or clutch.

  • Finance and write-offs

    MOT records don’t show outstanding finance or insurance write-offs. A history check does.

  • Test drive

    Listen for knocks over bumps, check every warning light goes out, and make sure the gears and brakes feel right.

Other years

Most years have their own guide. The year is when the car was first registered (it’s on the logbook, or check the reg below).

20212020201920182017201620152014201320122011201020092008200720062005200420032002200120001999199819971996199519941993199219911990

What usually goes wrong with a Mercedes-Benz SL?

We haven’t found widely reported faults for the Mercedes-Benz SL in the UK buying guides we use yet. That doesn’t mean it has none, so check the car carefully and look at the MOT weak spots below.

Common Mercedes-Benz SL MOT failures to check

Parts flagged at MOT well above the usual rate for cars the same age, in more than one year. From the DVSA’s results for every MOT done in Great Britain during 2023–2025.

  • Ball joint dust cover

    up to 3.5× usual

    Stands out on cars registered in 1994, 1997, 1998, 1999, 2000 and 2001.

    Rough price £60–£150 (one joint) ClickMechanic

    At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

  • Side repeaters

    up to 3.3× usual

    Stands out on cars registered in 1995, 1996, 1997, 1998, 1999 and 2000.

    Rough price £10–£80 our estimate

    At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.

  • Ball joint

    up to 3.4× usual

    Stands out on cars registered in 2016, 2017 and 2018.

    Rough price £60–£150 (one joint) ClickMechanic

    At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

  • Sub-frame

    up to 2.6× usual

    Stands out on cars registered in 1994 and 1997.

    Rough price £300–£1,000 our estimate

    At the viewing: Look underneath at the frame the suspension bolts to. Flaky rust or holes are expensive to fix.

  • Wheels

    up to 2.4× usual

    Stands out on cars registered in 2012 and 2015.

    Rough price £70–£150 our estimate

    At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.

  • Rigid brake pipes

    up to 1.8× usual

    Stands out on cars registered in 2013 and 2014.

    Rough price £100–£400 our estimate

    At the viewing: Ask to see underneath, or check the MOT advisories: corroded brake or fuel pipes get worse every year and fail the MOT when they do.

Mercedes-Benz SL MOT pass rate by year

Of the years since 2005 with plenty of MOT tests, the 2008 Mercedes-Benz SL did best (83% passed first time, 26 points above all 2008 cars) and the 2019 did worst (92%, 7 points above all 2019 cars). Older cars fail more, so compare each year with all cars registered the same year.

YearPass first timeAll cars that yearMOT tests
202092%87% +5340 (small sample)
201992%85% +71,021
201890%83% +71,199
201791%80% +111,909
201689%77% +122,304
201587%74% +132,389
201486%70% +163,166
201382%67% +153,382
201282%64% +181,246
201184%62% +22753
201080%60% +201,052
200981%59% +221,418
200883%57% +262,265
200781%57% +242,348
200681%56% +252,390
200582%57% +253,344
200483%57% +265,466
200381%57% +247,027
200281%58% +232,895
200183%60% +23855
200081%61% +201,444
199981%63% +181,608
199880%65% +152,055
199781%65% +161,994
199680%66% +141,742
199579%67% +121,614
199479%67% +121,166
199377%68% +9476 (small sample)
199282%69% +13351 (small sample)
199180%71% +9322 (small sample)
199081%72% +9208 (small sample)

Questions to ask the seller before buying a Mercedes-Benz SL

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

  1. Any recent work on the ball joint dust cover? (Flagged at MOT 3.5× as often on the Mercedes-Benz SL as on other cars the same age.)
  2. Any recent work on the side repeaters? (Flagged at MOT 3.3× as often on the Mercedes-Benz SL as on other cars the same age.)
  3. Any recent work on the ball joint? (Flagged at MOT 3.4× as often on the Mercedes-Benz SL as on other cars the same age.)
  4. Can I see the service history and receipts for any big jobs?

Looking at a Mercedes-Benz SL?

Check the actual car: its own MOT history, whether it already shows these weak spots and what to ask the seller. Free, no sign-up.

Where this comes from: MOT figures are the DVSA’s anonymised results for every MOT test done in Great Britain during 2023–2025, grouped by the year each car was first registered. How many are on the road is from the Department for Transport’s vehicle licensing statistics. Known faults are from UK buying guides, in our own words, with links. How we score