Lambretta LI150S: MOT pass rate by registration year

Which LI150S years pass first time, and which fall short of the model's 88.7% average, from 520 DVSA tests.

1964

highest-passing year · 91.6%

1963

lowest-passing year · 84.9%

6.7pp

spread across 4 years

Pass rate by registration year

first-time pass rate · cohorts with 50 or more tests · registration year from first use date

Highest pass rate: 1964 (91.6% of 226 tests). Lowest: 1963 (84.9% of 93). Years more than two points below the model average: 1963, 1965.

Registered	Tests	First-time pass	vs model (88.7%)
1963	93	84.9%	-3.8 pp
1964	226	91.6%	+2.9 pp
1965	111	86.5%	-2.2 pp
1966	55	89.1%	+0.4 pp

Older cohorts are survivors: the worst examples have already left the road, which tends to lift the earliest years. A first-time MOT pass is a roadworthiness check, not a full mechanical inspection.

Pass rate over time

first-time pass rate by test year · 2008–2017

Questions

Which LI150S years have the lowest MOT pass rate?: 1963, 1965 registered examples pass first time less often than the Lambretta LI150S overall (88.7%); the 1963 cohort is lowest at 84.9% from 93 tests.
Which LI150S year has the highest MOT pass rate?: 1964, at 91.6% of 226 first tests (2005–2025).
How much does the LI150S pass rate vary by year?: 6.7 percentage points between the highest (1964, 91.6%) and lowest (1963, 84.9%) cohorts with at least 50 tests. Older cohorts are survivors: the worst examples have already left the road, which tends to lift the earliest years.

Full report: Lambretta LI150S reliability, failures and mileage · ranked #1370 of 5428 models· other Lambretta models: LI125, GP200, LI150, GP150, GP125, Li