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Mercedes-benz A-class vs Mercedes-benz Sl 400 grand edition premium a: reliability comparison

MOT pass rates, common faults and mileage compared from real UK MOT data.

Mercedes-benz A-class
78%
MOT pass rate · 362,612 vehicles
Mercedes-benz Sl 400 grand edition premium a
92%
MOT pass rate · 175 vehicles
More reliable
Verdict: On MOT pass rate, the Mercedes-benz Sl 400 grand edition premium a is the more reliable of the two — 92% pass first time versus 78%. It's one signal among several; check the full breakdown below.

Head to head

Measure Mercedes-benz A-class Mercedes-benz Sl 400 grand edition premium a
MOT pass rate 78% 92% ✓
MOT failure rate 22% 8% ✓
Faults & advisories per test 1.6 0.4 ✓
Dangerous-fault share 3% ✓ 13%
Average mileage 86,210 mi 22,187 mi
Sample size (vehicles) 362,612 175

Most common faults

Mercedes-benz A-class

  1. Nearside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  2. Offside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  3. Nearside Front Tyre worn close to the legal limit (4.1.E.1)
  4. Under-trays fitted obscuring some underside components
  5. Offside Front Tyre worn close to the legal limit (4.1.E.1)
  6. Offside Rear Tyre slightly damaged/cracking or perishing (5.2.3 (d) (ii))

Mercedes-benz Sl 400 grand edition premium a

  1. Nearside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  2. Offside Front Tyre slightly damaged/cracking or perishing (5.2.3 (d) (ii))
  3. Nearside Front Tyre has a bulge, caused by separation or partial failure of its structure (5.2.3 (d) (ii))
  4. Offside Rear Tyre slightly damaged/cracking or perishing (5.2.3 (d) (ii))
  5. Offside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  6. Nearside Rear Nail in tyre

Reliability FAQ

On MOT pass rate, the Mercedes-benz Sl 400 grand edition premium a is the more reliable of the two — 92% pass first time versus 78%. It's one signal among several; check the full breakdown below.

Full Mercedes-benz A-class report Full Mercedes-benz Sl 400 grand edition premium a report Most reliable cars

Pass rates are computed over completed (pass/fail) MOT tests. Reliability also depends on age, mileage and upkeep — see each model's page for the full picture.