Porsche 928 MOT Pass Rate
Overall pass rate across all manufacture years, based on 16,768 real MOT test results. Failure rate: 29.1%.
Data from official DVSA MOT testing records
Porsche 928 MOT Reliability Overview
The Porsche 928 is a relatively common sight on UK roads, with 16,768 MOT test results recorded in our database spanning 18 manufacture years. It has an overall MOT pass rate of 70.9% and a failure rate of 29.1%, which is above the UK average of approximately 37%.
Based on this data, the Porsche 928 earns a "Very Good" reliability rating. The average Porsche 928 presents for MOT with approximately 106,075 miles on the clock. Manufacture year matters: 1978 models achieve the highest pass rate at 76.0%, while 1981 models have the lowest at 62.7%. This 13.3 percentage point difference suggests notable variation in build quality or component durability across production years.
The most common MOT failure for the Porsche 928 is Lamps, Reflectors and Electrical Equipment, affecting 19.5% of all tests. Lighting failures cover all external lights: headlights, tail lights, brake lights, indicators, fog lights, and reflectors. A single blown bulb will cause an MOT fail. This is one of the most preventable failure categories. The second most common issue is Brakes at 18.6%. Suspension rounds out the top three at 15.0%. Together, these top 3 failure categories account for a significant portion of all MOT failures for this model.
Top failures across all manufacture years combined. Individual year pages may show different top failures.
What Fails Most
Best Year to Buy
📈 How Each Vintage Ages
Tracking how each manufacture year's MOT pass rate changes as the car ages. Showing 6 vintages — click year chips to highlight.
Multi-line chart showing how different Porsche 928 vintages degrade over time, from age 3 to 38 years.
Only vintages with 100+ tests in at least 3 different test years are shown. Fleet average is the UK-wide pass rate for all cars at each age.
📉 How Age Affects Reliability
MOT failure rate by vehicle age for the Porsche 928. The dashed red line marks when the manufacturer warranty typically expires (3 years).
Line chart showing MOT failure rate by vehicle age from 16 to 20 years, with warranty expiry marked at 3 years.
💡 What does the warranty cliff mean?
The Porsche 928 shows a relatively stable failure rate after warranty — the change of 0% is negligible. Peak failure occurs at age 16 (37.6% fail rate).
Note: pass rates may improve for very old vehicles due to survivorship bias — only well-maintained cars remain on the road.
Pass Rate by Manufacture Year
* High Fail Rate badge indicates an MOT pass rate below 65% (failure rate above 35%).
What Fails on This Car?
Click a category to see specific failure items.
View as table
| Rank | Failure Category | Rate (%) | Count |
|---|---|---|---|
| 1 | Lamps, Reflectors And Electrical Equipment | 35.2% | 5,892 |
| 2 | Brakes | 24.4% | 4,088 |
| 3 | Suspension | 18.0% | 3,018 |
| 4 | Tyres | 11.4% | 1,915 |
| 5 | Driver's View Of The Road | 9.2% | 1,546 |
| 6 | Steering | 9.0% | 1,509 |
| 7 | Exhaust, Fuel And Emissions | 6.2% | 1,042 |
| 8 | Noise, Emissions And Leaks | 4.0% | 672 |
| 9 | Non-component Advisories | 2.9% | 479 |
| 10 | Visibility | 2.7% | 452 |
| 11 | Body, Chassis, Structure | 2.4% | 406 |
| 12 | Seat Belts And Supplementary Restraint Systems | 1.7% | 291 |
| 13 | Registration Plates And Vin | 1.7% | 286 |
| 14 | Body, Structure And General Items | 1.5% | 253 |
Failures per 10,000 Miles
avg. 106,075 miFor every 10,000 miles driven, this shows what percentage of MOT tests fail for each category. This accounts for how far cars are actually driven, not just raw pass/fail counts.
View as table
| Category | Rate / 10K mi | Raw % | Count |
|---|---|---|---|
| Lamps & Electrical | 3.32 | 35.2% | 5,892 |
| Brakes | 2.30 | 24.4% | 4,088 |
| Suspension | 1.70 | 18.0% | 3,018 |
| Visibility | 1.12 | 11.9% | 1,998 |
| Tyres | 1.08 | 11.4% | 1,915 |
| Steering | 0.85 | 9.0% | 1,509 |
| Emissions & Exhaust | 0.59 | 6.2% | 1,042 |
| Noise, emissions and leaks | 0.38 | 4.0% | 672 |
| Body & Structure | 0.37 | 3.9% | 659 |
| Non-component advisories | 0.27 | 2.9% | 479 |
| Seat Belts | 0.16 | 1.7% | 291 |
| Registration Plates and VIN | 0.16 | 1.7% | 286 |
🚗 Similar Cars to Consider
Mileage at MOT
The average Porsche 928 has 106,075 miles when tested for MOT.
📊 Mileage-Adjusted Failure Rate
How often this car fails MOT relative to how much it's driven — a fairer comparison than raw pass rate.
The Porsche 928 has a mileage-adjusted failure rate of 2.74% per 10,000 miles driven. The average across all makes is 5.38%, so this model is better than average.
About Porsche 928 MOT Data
The Porsche 928 is a relatively common sight on UK roads, with 16,768 MOT test results recorded in our database spanning 18 manufacture years. It has an overall MOT pass rate of 70.9% and a failure rate of 29.1%, which is above the UK average of approximately 37%.
For Porsche 928 owners, these results suggest a reliable vehicle that generally passes its MOT without major issues. Focus your pre-MOT checks on lamps, reflectors and electrical equipment and brakes for the best chance of a first-time pass. Use our detailed year-by-year breakdown and failure analysis below to understand how your specific 928 is likely to perform.
Lamps, Reflectors and Electrical Equipment — 19.5% of failures
Lamps, Reflectors and Electrical Equipment issues account for 19.5% of MOT failures on the Porsche 928. Lighting failures cover all external lights: headlights, tail lights, brake lights, indicators, fog lights, and reflectors. A single blown bulb will cause an MOT fail. This is one of the most preventable failure categories. Typical repair costs: £5–50. Pre-MOT check: Walk around the car and check every light — headlights (dipped and main beam), side lights, tail lights, brake lights, indicators, hazard lights, reverse light, rear fog light, and number plate lights. Replace any blown bulbs before the test.
Brakes — 18.6% of failures
Brakes issues account for 18.6% of MOT failures on the Porsche 928. Brake-related failures include worn brake pads, corroded brake discs, leaking brake lines, and faulty brake servos. These are safety-critical components — any brake deficiency will result in an MOT fail. Typical repair costs: £150–400. Pre-MOT check: Listen for squealing or grinding noises. Check brake pedal feel — if it feels spongy or goes to the floor, have the system inspected immediately. Look at brake pad thickness through the wheel spokes (minimum 3mm).
Suspension — 15.0% of failures
Suspension issues account for 15.0% of MOT failures on the Porsche 928. Suspension failures typically involve worn bushes, leaking shock absorbers, broken coil springs, and damaged suspension arms. These affect ride quality, tyre wear, and road holding. Typical repair costs: £200–500. Pre-MOT check: Look for uneven tyre wear, listen for clunking over bumps, and check if the car pulls to one side. A bouncy ride suggests worn shock absorbers. Visually inspect coil springs for cracks.
Frequently Asked Questions
What is the MOT pass rate for the Porsche 928?
Based on 16,768 MOT tests in our database, the Porsche 928 has an overall pass rate of 70.9% (29.1% fail rate).
What are the most common MOT failures on a Porsche 928?
The top 3 reasons a Porsche 928 fails its MOT are: 1. Lamps, Reflectors and Electrical Equipment (19.5%), 2. Brakes (18.6%), 3. Suspension (15.0%). Check these areas before booking your MOT.
Is the Porsche 928 reliable?
With a 29.1% MOT failure rate, the 928 is more reliable than average compared to the UK average of ~40%.
What should I check before an MOT on my Porsche 928?
Based on failure data, focus on: Lamps, Reflectors and Electrical Equipment (19.5%); Brakes (18.6%); Suspension (15.0%). These are the areas most likely to cause a fail. Also check all lights, tyres (minimum 1.6mm tread), and windscreen condition — these are quick wins that apply to all cars.
Based on DVSA anonymised MOT test data (2005–2024). Crown copyright, Open Government Licence v3.0.