Mercedes Benz
7,393 MOT tests analysed. sits above the UK fleet average — here's where GLs pass, fail, and end up on the retest sheet.
That's 8.0 points above the UK fleet average across our 1,984 tracked models — a confident result.
Pass
85.5%
Pass-after-fix
3.1%
Fail
10.6%
Avg miles
98,611
Pass + Pass-after-fix + Fail = 100%
Some examples of this model are borderline — a small number of diesels were certified Euro 6 before September 2015. Check your registration on the government's ULEZ checker to be certain. Daily charges if driven in the zone: London £12.50 · Birmingham £8.00 · Bristol £9.00 .
Performance by cohort
2 year bands · 7,322 tests
Pass rate climbs 10.7 points across the cohorts — newer GL examples clear the test more reliably than the early cars.
Pass
85.0%
Fail
10.9%
PRS
3.2%
Avg mileage at test
101,534 mi
Pass
95.7%
Fail
3.9%
PRS
0.0%
Avg mileage at test
37,997 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
Across 3,805 MOT tests, the Gl returns 82.0% first-time pass — above the UK fleet average. The single most-logged Major fail is a split CV-joint boot. Windscreen damage and tyre tread under the limit round out the top three. Average tested mileage sits at 93,580, which is the lens to read those failure rankings through. If you own one and the next test is close, the ranked list below is a sensible pre-test checklist.
ABI Insurance Group
A high-group car — insurance costs will be significantly above average. Lower groups cost less to insure; UK fleet average is around Group 22.
Source: ABI Group Rating Panel · administered by Thatcham Research · groups cover standard variants; performance trims may sit higher. Browse all insurance groups →
38–48
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A transmission shaft constant velocity joint boot severely deteriorated
344 occurrences · 4.7% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
164 occurrences · 2.2% of tests
Tyre tread depth not in accordance with the requirements
163 occurrences · 2.2% of tests
A rear registration plate lamp or light source missing or inoperative in the case of multiple lamps or light sources
105 occurrences · 1.4% of tests
A tyre cords visible or damaged
100 occurrences · 1.4% of tests
Reflector defective or damaged by up to 50% of the reflecting surface
92 occurrences · 1.2% of tests
A tyre seriously damaged
71 occurrences · 1.0% of tests
A transmission shaft constant velocity joint boot missing or no longer prevents the ingress of dirt etc
63 occurrences · 0.9% of tests
Brake pipe damaged or excessively corroded
59 occurrences · 0.8% of tests
a brake lining or pad worn below 1.5mm
48 occurrences · 0.6% of tests
Counts cover Major and Dangerous defects logged at test. Advisory items excluded so this shows why a car was rejected, not just what the tester flagged in passing.
Worst-case fix budget · top 3 failures
£128–£225
If every one of this GL's most-logged Major fails hit at the same MOT, that's the real-world UK garage range. Reality is usually one or two items, not all of them. Open the estimator →
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Build your own retest budget.
Year-band analysis
First-time MOT pass rate split by registration band. A 10.7-point gap between bands means the year you buy Mercedes Benz GL has a real effect on what turns up at the garage.
Best band to buy
95.7%
2018–2020 registration
the 2018–2020 band climbs to 95.7% — a 10.7-point improvement. Tests in this band average 37,997 miles — roughly 64K miles fewer on the clock than the older band. Failures here are mostly wear items: less than 1.5 mm thick, damaged but not adversely affecting driver's view — the structural issues that drag down older examples don't appear in the top-10 for this band. The stricter post-2018 MOT test rules meant manufacturers had to tighten up emissions and electrical checks, but this band still shows far fewer major failures on suspension and bodywork than the older fleet.
Band to be cautious about
85.0%
Pre-2018 registration
On the older band (pre-2018), the data shows a 85.0% pass rate against a fleet average of 95.7% on the newer band. The main culprits logged at test: constant velocity boot severely deteriorated, tread depth below requirements of 1.6mm, and damaged but not adversely affecting driver's view. Average mileage on test for this band is 101,534 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2018-2020 (95.7% first-time pass). Worst band to avoid: pre-2018 (85.0% pass). That's a 10.7-point spread across 7,064 older tests and 258 newer ones — year of build makes a material difference on this model.
Picked against this car's top failure patterns. Affiliate links to Amazon UK — we earn a small cut at no cost to you. Disclosed up-front, doesn't shape the data.
Item 01 · Amazon UK
Digital tyre-tread depth gauge
Five quid for a gauge beats £150 for a retest. UK MOT minimum is 1.6mm — most testers fail anything below 2mm to be safe.
Search Amazon UK
Item 02 · Amazon UK
H7 / W21W bulb pack
A spare-bulb kit lives in the boot. Test morning is not the time to find your stop-lamp's gone.
Search Amazon UK
My Motor World · affiliate
Affiliate links — small commission, no extra cost to you.
Click Mechanic · affiliate
Affiliate links — small commission, no extra cost to you.
Mobile mechanic · UK-wide
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Recall history
The GL has 5 official UK vehicle recalls covering defect details, remedies, and affected build dates.
Use the failure ranking as a pre-test checklist or a haggling lever. Treat the headline pass rate as a fleet-wide trend, not a guarantee on any individual car.
If you own a GL and your last MOT looked nothing like the ranked failures above, that's normal — individual cars vary widely. The ranking shows the patterns testers flag most often across the country.
