Petrol and diesel cars fail their MOT at almost the same rate, year for year, because the things that actually fail a test, corrosion, brakes, suspension, lights, don't care what fuel is in the tank. The real differences sit at the edges: electric cars fail more while young, and hybrids fail the least of any fuel type.
First-time MOT failure percentage by age, 2025 data. Petrol and diesel are built on 13.3 million and 8.7 million tests; hybrid on 1.36 million; electric on just 437,563, so the electric line is the noisiest of the four, and it stops at age 13 because few electric cars are older than that yet. Read the electric and hybrid lines against petrol and diesel only at the ages where all four overlap.