The picture
Mongrel 125: middle-of-the-pack on first-time pass
Across 777 MOT tests, the Mongrel 125 returns 72.8% first-time pass — below the UK fleet average. The single most-logged Major fail is brake efficiency below minimum requirement. Direction indicator lamp missing and a stop-lamp out round out the top three. Average tested mileage sits at 4,922, 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.
Top ten reasons for rejection.
- 01
Brake efficiency below minimum requirement
32 occurrences · 4.1% of tests
- 02
A direction indicator lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning
23 occurrences · 3.0% of tests
- 03
Stop lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning
21 occurrences · 2.7% of tests
- 04
Reflector missing or reflecting white to the rear
17 occurrences · 2.2% of tests
- 05
A headlamp missing, inoperative or more than ½ not functioning in the case of LED
12 occurrences · 1.5% of tests
- 06
A tyre not fitted in accordance with the direction of rotation marked on the side wall
12 occurrences · 1.5% of tests
- 07
Brake lining or pad worn below 1.0mm
11 occurrences · 1.4% of tests
- 08
On a motorcycle with two front or rear wheels, there is inadequate braking effort at a wheel
11 occurrences · 1.4% of tests
- 09
A lamp missing or inoperative
11 occurrences · 1.4% of tests
- 10
A wheel bearing with excessive play
11 occurrences · 1.4% 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 2 failures
£18–£115
If every one of this Mongrel 125'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.
Tools that pre-empt a retest.
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
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
Item 02 · Amazon UK
Headlight restoration kit
Yellowed lenses fail the light-output test. A restoration kit lifts the haze in an afternoon for £20.
Search Amazon UK
Buying or keeping a Mongrel 125?
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 Mongrel 125 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.