1999 Mercedes-Benz SL MOT pass rate, common failures & what to check

In 2025, 81.6% of Mercedes-Benz SLs first used in 1999 passed their MOT first time, against 64.6% for all cars first used in 1999. Across 1,623 SL first tests from 2023 to 2025, the most common failure areas were lamps and electrical equipment, suspension and brakes.

This page analyses first MOT tests for Mercedes-Benz SLs first used in 1999 (all trims grouped): 2021 to 2025 for the pass-rate trend, and 2023 to 2025 for the failure and advisory analysis — plus what is worth checking before you buy one.

Data: DVSA anonymised MOT tests to December 2025 · Calculated by SortedCars · Updated October 2026

Passed first time, 2025
81.6%
of 523 first tests; all cars first used in 1999: 64.6%. Fixed-at-the-test counts as a fail
Tests analysed
1,623
first tests, 2023–2025; 523 in 2025
Clean pass, 2025
47.6%
of 523 first tests in 2025, passed with no advisory and no minor defect recorded
Typical mileage, tested in 2025
82,000
middle half: 56,500–101,000 miles; all cars first used in 1999: 98,000

How the 1999 Mercedes-Benz SL MOT pass rate has changed

Share of first tests passed in each year, SLs first used in 1999 against all cars first used in 1999 (any make or fuel; not adjusted for mileage, fuel or use). In 2025 the SL figure was 17.0 points higher.

1999 SLAll cars first used in 1999
50%60%70%80%90%20212022202320242025Test year (first tests)All cars first used in 1999, test year 2021: 58.5%All cars first used in 1999, test year 2022: 60.7%All cars first used in 1999, test year 2023: 62.5%All cars first used in 1999, test year 2024: 63.2%All cars first used in 1999, test year 2025: 64.6%1999 SL, test year 2021: 82.7%1999 SL, test year 2022: 84.2%1999 SL, test year 2023: 81%1999 SL, test year 2024: 81.3%1999 SL, test year 2025: 81.6%81.6%64.6%
View this chart as a table
Test year1999 SLAll cars first used 1999SL first tests
202182.7%58.5%649
202284.2%60.7%596
202381.0%62.5%554
202481.3%63.2%546
202581.6%64.6%523

Common 1999 Mercedes-Benz SL MOT failures

Share of the 303 failed first tests (2023–2025) with at least one failure in each area. A test can fail in more than one area, so the shares add up to more than 100%.

Lamps, reflectors and electrical equipment41.3%
Suspension32.0%
Brakes21.1%
Visibility20.1%
Tyres14.2%
Noise, emissions and leaks10.2%

Most common failure items

DVSA failure itemShare of failed first testsTests
Ball joint dust cover: no longer prevents the ingress of dirt19.5%59

Item names are DVSA’s own wording. 2023–2025 combined.

What to check on a 1999 Mercedes-Benz SL before buying

The three areas where failed first tests most often had a fault, 2023–2025.

  1. Lamps and electrics. Ask someone to watch while you work the brake lights, indicators, sidelights, dipped and main beam, and the number-plate lamps.
  2. Suspension. Worth looking behind the front wheels with a torch at the coil springs, and listening for knocks over bumps on the test drive.
  3. Brakes. Worth looking at the discs and pads through the wheel spokes for scoring and a worn lip, and noticing on the test drive whether the car pulls to one side or the pedal feels long.

Common 1999 Mercedes-Benz SL MOT advisories

Advisories are points the tester noted that did not fail the car. Most common on 1999 SLs, as a share of all 1,623 first tests, 2023–2025.

DVSA advisory itemShare of first testsTests
Rigid brake pipes: corroded, covered in grease or other material13.6%220
Engine oil leaks: leak, but not excessive9.3%151
Tyre condition: slightly damaged/cracking or perishing8.3%135
Sub-frame: corroded but not seriously weakened5.6%91
Tread depth: worn close to legal limit/worn on edge5.3%86

Questions about the 1999 Mercedes-Benz SL MOT

What is the MOT pass rate of a 1999 Mercedes-Benz SL?

In 2025, 81.6% of SLs first used in 1999 passed their MOT first time, against 64.6% for all cars first used in 1999. A car fixed during the test counts as a fail.

What does a 1999 SL most often fail its MOT on?

Lamps and electrical equipment (in 41.3% of failed first tests, 2023–2025), suspension (32.0%) and brakes (21.1%). The single most common item was “Ball joint dust cover: no longer prevents the ingress of dirt” (19.5%).

How often does a 1999 Mercedes-Benz SL fail its MOT?

In 2025, 18.4% of first tests on SLs first used in 1999 did not pass first time: 15.3% failed, and a further 3.1% had a fault fixed during the test (counted as a fail here). Across 2023–2025, 303 of 1,623 first tests did not pass first time.

What are the most common 1999 Mercedes-Benz SL MOT advisories?

“Rigid brake pipes: corroded, covered in grease or other material” (on 13.6% of first tests, 2023–2025), “Engine oil leaks: leak, but not excessive” (9.3%), “Tyre condition: slightly damaged/cracking or perishing” (8.3%), “Sub-frame: corroded but not seriously weakened” (5.6%) and “Tread depth: worn close to legal limit/worn on edge” (5.3%).

Is a 1999 Mercedes-Benz SL reliable?

An MOT pass rate shows what failed at the test, not how reliable a car is. For this group of cars the first-time pass rate went from 82.7% in 2021 to 81.6% in 2025. For one particular car, its own MOT history matters more than the average.

Other cars first used in 1999

The most-tested cars from the same year. Each page uses the same method.

1999 Volkswagen Transporter MOT statistics · 1999 Land Rover Defender MOT statistics · 1999 BMW Z3 MOT statistics · 1999 BMW 3 Series MOT statistics · 1999 Volkswagen Golf MOT statistics

How the 1999 Mercedes-Benz SL MOT data is calculated

Every number on this page is calculated by SortedCars from DVSA’s anonymised MOT test data for Great Britain, 2021–2025. “1999 SL” means a Mercedes-Benz SL whose date of first use falls in 1999 (S, T and V plates), all trims grouped. Class 4 vehicles, first tests only — retests are not counted. Pass rate = passed ÷ all first tests; a car with a fault fixed during the test (PRS) counts as a fail. Our national first-test pass rate matches DVSA’s published figure (table DVSA/MOT/01) to within 0.04 points in every year. Clean pass = passed with no advisory and no minor defect recorded. Mileage is the reading recorded at the test. Comparisons are with all cars first used in 1999, any make or fuel, and are not adjusted for mileage, fuel or use. Failure and advisory item names are DVSA’s own wording. No figure is shown for fewer than 500 tests; an item is shown only if it appears on at least 50 tests and 1% of the base. Pass rates describe a group of cars, not one car: a well-kept example can pass and a neglected one can fail. This page is general information, not advice about any particular vehicle; always have a used car inspected before you buy. SortedCars is not affiliated with or endorsed by DVSA. You can check any car’s MOT history free on the official service: gov.uk/check-mot-history. Contains public sector information licensed under the Open Government Licence v3.0.