How MOT Pass Rate Scoring Works

What the score represents

The base score is the percentage of MOT tests that passed, including tests that passed after a fail. The score is then adjusted downward for specific risk signals, so the final value reflects both reliability and repair risk.

How we calculate the base pass rate

• We count total MOT tests on record.
• We count passes, fails, and passes after a fail.
• Base pass rate = (passes + passes after fail) / total tests.

Score adjustments and why they exist

These adjustments are small, but they help flag cars that may cost more to keep on the road. Each adjustment is applied once per trigger.

• High advisories (-10%) Multiple advisories on key safety items can signal near-term repair spend.
• Each pass after fail (-5%) A quick retest pass suggests issues that required fixes, so it lowers confidence.
• Each high-priority MOT keyword (-5%) Serious defect keywords (brakes, steering, corrosion, tyres) indicate safety risk.
• Mileage inconsistency (-5%) Unusual mileage drops can suggest odometer errors or history gaps.
• 100k+ miles (-5%) Higher mileage is linked to wear on suspension, drivetrain, and rubber components.
• Age 10+ years (-5%) Age increases the chance of corrosion and age-related failures.

Example

A car with 5 total tests and 4 passes has a base pass rate of 80%. If it also has 1 pass-after-fail and is over 10 years old, the score is adjusted down by 10% (two adjustments of -5%), resulting in a 70% score.

Use it as a guide, not a verdict

The score is a quick indicator, not a definitive judgment. Always review the full MOT history and vehicle condition, especially if the score is low.

Want the short version?

We also publish a shorter overview in the blog section with the same scoring rules.