Money-Saving MOT Tips, Backed by the Data
How much warning do you actually get before an ignored advisory becomes a fail?
Nationally, the average gap between an advisory first being flagged and it progressing to a fail on the same vehicle is 7,536 miles. By component: Tyres 8,266 mi | Suspension 7,388 mi | Brakes 7,379 mi | Lighting 6,983 mi | Steering 6,885 mi | Exhaust & Emissions 6,582 mi | Body & Structure 5,508 mi.
Note: This is a mileage gap, not a time or cost figure - there’s no repair-cost data anywhere in this dataset, and MOT cadence is annual by law so "12 months" isn’t how the data is actually measured.
What’s the single best model year to buy for a popular model, based on failure data?
For the Ford Fiesta, 2021 is the strongest year at a 5.9% failure rate, from 49,545 tests - among years with at least 5,000 tests, so the figure is well-supported.
Note: Always apply a sample-size floor - a thinly-tested recent year can look artificially good.
How can you spot a "clocked" (mileage-tampered) car using MOT history alone?
Mileage should only ever go up between tests - a reading that drops, or a suspicious gap in the test history, are the two biggest tells. Read every recorded test in order, not just the latest figure.
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