Is the Mercedes-Benz SL reliable?

On MOT evidence the Mercedes-Benz SL is well above average. It passes 84.1% of tests once age and mileage are accounted for, against a national average of 72.3%. That figure covers 67% of the national age and mileage range, which is enough to quote but not to rank. This measures how often the car meets the MOT standard, not how often it breaks down or what a repair costs.

What is the most common MOT failure on a Mercedes-Benz SL?

The item recorded most often is "A suspension joint dust cover missing or no longer prevents the ingress of dirt etc", which appears in 10.0% of failed Mercedes-Benz SL tests. Because one failed test can list several items, these shares do not add up to 100%.

What do testers most often warn about on a Mercedes-Benz SL?

The most common advisory is "Brake pipe damaged or excessively corroded", noted on 13.5% of all Mercedes-Benz SL tests. An advisory is not a failure: it flags something that will likely need attention before the next test.

What mileage does a Mercedes-Benz SL usually have at its MOT?

The average odometer reading recorded at test is 68,111 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.

Does a Mercedes-Benz SL get harder to pass as it ages?

Yes. At 3 to 5 years old, 91.6% of Mercedes-Benz SL tests pass. By fifteen years or more, that falls to 81.3%. Nearly every model follows this pattern, which is why comparing raw pass rates between models is misleading unless age is accounted for.

Model reliability file

Mercedes-Benz SL MOT pass rate & common failures

From 20,815 recorded MOT tests of the Mercedes-Benz SL, published by DVSA.

Data updated 29 July 2026

Quick answer

The Mercedes-Benz SL passes 84.1% of MOT tests once results are adjusted for the age and mileage of the cars tested, against a national average of 72.3%. That is well above average. Based on 20,815 tests. Its most commonly recorded failure is suspension joint dust cover missing or no longer prevents the ingress of dirt etc, which appears in 10.0% of failed tests. Cars of this model average 68,111 miles on the odometer when tested.

At a glance

Pass rate, adjusted for age and mileage

84.1%national average72.3%unadjusted83.0%range covered67%

The SL is 11.8 percentage points above the national pass rate once age and mileage are accounted for, which is well above average. The unadjusted figure is 83.0%; the difference is what the age and mileage of this model’s fleet was hiding.

DVSA recorded wording

Most common failure items

Share of failed Mercedes-Benz SL tests in which each item was recorded. One failed test often lists several items, so these do not sum to 100%.

1.A suspension joint dust cover missing or no longer prevents the ingress of dirt etc10.0%
304 occurrencesSuspension joint dust cover missing or split explained
2.A suspension pin, bush or joint excessively worn9.8%
300 occurrencesSuspension arm bush worn explained
3.A tyre seriously damaged9.8%
298 occurrencesTyre damaged or deteriorated explained
4.A tyre cords visible or damaged9.2%
281 occurrencesTyre ply or cord exposed, or the casing separating explained
5.A spring or spring component fractured or seriously weakened8.7%
267 occurrencesRoad spring broken or fractured explained
6.A tyre seriously damaged7.6%
232 occurrencesTyre damaged or deteriorated explained
7.Brake pipe damaged or excessively corroded7.3%
222 occurrencesBrake pipe corroded explained
8.Tyre tread depth not in accordance with the requirements5.7%
173 occurrencesTyre worn close to the legal limit explained
9.Wiper blade missing or obviously not clearing the windscreen5.4%
164 occurrencesWiper or washer not working properly explained
10.Engine MIL illuminated indicating a malfunction4.2%
129 occurrencesEngine management light on, or not working explained

Warnings without a failure

Most common advisories

Share of all Mercedes-Benz SL tests carrying each advisory. The denominator differs from the failure list above because an advisory can be issued on a car that passed.

1.Brake pipe damaged or excessively corroded13.5%
2,800 testsBrake pipe corroded explained
2.Tyre tread depth not in accordance with the requirements12.8%
2,656 testsTyre worn close to the legal limit explained
3.A tyre seriously damaged12.1%
2,525 testsTyre damaged or deteriorated explained
4.Brake disc or drum excessively weakened, insecure or fractured8.1%
1,678 testsBrake disc worn, pitted or scored explained
5.Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users6.1%
1,279 tests
6.A suspension pin, bush or joint excessively worn4.6%
949 testsSuspension arm bush worn explained
7.A brake lining or pad worn below 1.5mm4.4%
908 testsBrake drum or shoe worn or contaminated explained
8.A wheel bearing with excessive play3.5%
732 testsWheel bearing has excessive play or is rough explained

How wear changes the picture

Pass rate by vehicle age

3–5 yrs92%

6–8 yrs92%

9–11 yrs87%

12–14 yrs82%

15+ yrs81%

Bands holding too few tests to be meaningful are omitted rather than shown as a rate.

What gets tested

The SL fleet

Average mileage recorded at test: 68,111
Fuel mix of tested cars: Petrol99.9%

Trim names grouped into this model (20)

Recorded exactly as DVSA holds them. Trim-level names are rolled up so one model is not split across a dozen thin pages.

AMG SL 43 PREMIUM MHEV AUTO
AMG SL 43 TOURING + MHEV AUTO
AMG SL 55 4MATIC+ PREMIUM + A
AMG SL 55 4MATIC+ TOURING + A
AMG SL 63 4MATIC+ PREMIUM + A
SL 320
SL 350
SL 350 CONVERTIBLE
SL 400
SL 400 GRAND EDITION AUTO
SL 400 GRAND EDITION PREMIUM A
SL 500
SL 500 GRAND EDITION AUTO
SL 500 GRAND EDITION PREMIUM A
SL 55 AMG
SL 560
SL 600
SL 63
SL AUTO
SL SPORTS

Check a specific Mercedes-Benz SL

A model average tells you the pattern. Its own MOT record tells you the car.

Compare within the range

Other Mercedes-Benz models

Mercedes-Benz A-Class — 73.3% adjusted
Mercedes-Benz C-Class — 77.0% adjusted
Mercedes-Benz E-Class — 78.5% adjusted
Mercedes-Benz GLA — 82.3% adjusted
Mercedes-Benz Vito — 71.0% adjusted
Mercedes-Benz GLC — 85.9% adjusted
All Mercedes-Benz models

Similar test volumes

Compare against other makes

Fiat 500L — 63.6% adjusted, ranked 235
Citroen C4 Cactus — 69.0% adjusted, ranked 180
Skoda Rapid — 73.4% adjusted, ranked 128
BMW 6 Series — 81.4% adjusted, ranked 46

Common questions

Is the Mercedes-Benz SL reliable?: On MOT evidence the Mercedes-Benz SL is well above average. It passes 84.1% of tests once age and mileage are accounted for, against a national average of 72.3%. That figure covers 67% of the national age and mileage range, which is enough to quote but not to rank. This measures how often the car meets the MOT standard, not how often it breaks down or what a repair costs.
What is the most common MOT failure on a Mercedes-Benz SL?: The item recorded most often is "A suspension joint dust cover missing or no longer prevents the ingress of dirt etc", which appears in 10.0% of failed Mercedes-Benz SL tests. Because one failed test can list several items, these shares do not add up to 100%.
What do testers most often warn about on a Mercedes-Benz SL?: The most common advisory is "Brake pipe damaged or excessively corroded", noted on 13.5% of all Mercedes-Benz SL tests. An advisory is not a failure: it flags something that will likely need attention before the next test.
What mileage does a Mercedes-Benz SL usually have at its MOT?: The average odometer reading recorded at test is 68,111 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.
Does a Mercedes-Benz SL get harder to pass as it ages?: Yes. At 3 to 5 years old, 91.6% of Mercedes-Benz SL tests pass. By fifteen years or more, that falls to 81.3%. Nearly every model follows this pattern, which is why comparing raw pass rates between models is misleading unless age is accounted for.

How this was worked out

Method and limits

Figures come from the DVSA anonymised MOT testing dataset, published under the Open Government Licence. Only class 4 initial tests are counted: retests are excluded so a car appears once, and abandoned tests are excluded entirely. The adjusted rate is directly standardised across twenty-five age and mileage bands and reweighted onto the national distribution, so this model is compared against cars that have lived a similar life rather than against a younger or lighter-used fleet.

An MOT measures whether a car met a legal standard on the day. It is not a breakdown record, a service history or a running-cost estimate, and a pass rate is a property of a fleet rather than a prediction about one car.