Is the Porsche 911 reliable?

On MOT evidence the Porsche 911 is well above average. It passes 89.5% of tests once age and mileage are accounted for, against a national average of 72.3%. That figure covers 78% of the national age and mileage range, which is enough to quote but not to rank. This measures how often the car meets the MOT standard, not how often it breaks down or what a repair costs.

What do testers most often warn about on a Porsche 911?

The most common advisory is "Tyre tread depth not in accordance with the requirements", noted on 11.2% of all Porsche 911 tests. An advisory is not a failure: it flags something that will likely need attention before the next test.

What mileage does a Porsche 911 usually have at its MOT?

The average odometer reading recorded at test is 57,530 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.

Does a Porsche 911 get harder to pass as it ages?

Yes. At 3 to 5 years old, 95.9% of Porsche 911 tests pass. By fifteen years or more, that falls to 85.4%. Nearly every model follows this pattern, which is why comparing raw pass rates between models is misleading unless age is accounted for.

Model reliability file

Porsche 911 MOT pass rate & common failures

From 51,870 recorded MOT tests of the Porsche 911, published by DVSA.

Data updated 29 July 2026

Quick answer

The Porsche 911 passes 89.5% of MOT tests once results are adjusted for the age and mileage of the cars tested, against a national average of 72.3%. That is well above average. Based on 51,870 tests. Its most commonly recorded failure is lambda coefficient outside the default limits or the range specified by the manufacturer, which appears in 11.3% of failed tests. Cars of this model average 57,530 miles on the odometer when tested.

At a glance

Pass rate, adjusted for age and mileage

89.5%national average72.3%unadjusted89.0%range covered78%

The 911 is 17.2 percentage points above the national pass rate once age and mileage are accounted for, which is well above average. The unadjusted figure is 89.0%; the difference is what the age and mileage of this model’s fleet was hiding.

DVSA recorded wording

Most common failure items

Share of failed Porsche 911 tests in which each item was recorded. One failed test often lists several items, so these do not sum to 100%.

1.Lambda coefficient outside the default limits or the range specified by the manufacturer11.3%
543 occurrencesEmissions above the permitted limit explained
2.A transmission shaft constant velocity joint boot missing or no longer prevents the ingress of dirt etc10.7%
516 occurrencesDriveshaft CV joint gaiter split or missing explained
3.Brake pipe damaged or excessively corroded9.2%
441 occurrencesBrake pipe corroded explained
4.Tyre tread depth not in accordance with the requirements9.1%
439 occurrencesTyre worn close to the legal limit explained
5.A tyre cords visible or damaged8.7%
420 occurrencesTyre ply or cord exposed, or the casing separating explained
6.A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning8.2%
396 occurrencesLamp not working explained
7.A tyre seriously damaged8.2%
396 occurrencesTyre damaged or deteriorated explained
8.The aim of a headlamp is not within limits laid down in the requirements7.0%
338 occurrencesHeadlamp aim incorrect explained
9.The aim of a headlamp is not within limits laid down in the requirements5.4%
258 occurrencesHeadlamp aim incorrect explained
10.An obligatory rear fog lamp missing, or a front or rear fog lamp inoperative or in the case of a multiple light source more than 1/2 not functioning5.3%
256 occurrencesLamp not working explained

Warnings without a failure

Most common advisories

Share of all Porsche 911 tests carrying each advisory. The denominator differs from the failure list above because an advisory can be issued on a car that passed.

1.Tyre tread depth not in accordance with the requirements11.2%
5,818 testsTyre worn close to the legal limit explained
2.Brake pipe damaged or excessively corroded8.5%
4,431 testsBrake pipe corroded explained
3.Brake disc or drum excessively weakened, insecure or fractured7.4%
3,822 testsBrake disc worn, pitted or scored explained
4.A tyre seriously damaged7.0%
3,614 testsTyre damaged or deteriorated explained
5.Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users3.9%
2,029 tests
6.A suspension pin, bush or joint excessively worn1.8%
950 testsSuspension arm bush worn explained
7.Nail in tyre1.4%
720 tests
8.Tyre tread depth not in accordance with the requirements1.4%
710 testsTyre worn close to the legal limit explained

How wear changes the picture

Pass rate by vehicle age

3–5 yrs96%

6–8 yrs94%

9–11 yrs94%

12–14 yrs93%

15+ yrs85%

Bands holding too few tests to be meaningful are omitted rather than shown as a rate.

What gets tested

The 911 fleet

Average mileage recorded at test: 57,530
Fuel mix of tested cars: Petrol99.8%

Trim names grouped into this model (40)

Recorded exactly as DVSA holds them. Trim-level names are rolled up so one model is not split across a dozen thin pages.

911 4S
911 BLACK EDITION
911 CABRIOLET
911 CARRERA
911 CARRERA 2
911 CARRERA 2 CABRIO
911 CARRERA 2 COUP
911 CARRERA 2 COUPE
911 CARRERA 2 RS
911 CARRERA 2 S
911 CARRERA 2 S TIPT-IC S
911 CARRERA 2 S-A
911 CARRERA 2 TARGA
911 CARRERA 2 TIPTRONIC
911 CARRERA 2 TIPTRONIC S
911 CARRERA 2 TIPTRONICS
911 CARRERA 2S
911 CARRERA 2S S-A
911 CARRERA 4
911 CARRERA 4 AUTO
911 CARRERA 4 CABRIO
911 CARRERA 4 COUPE
911 CARRERA 4 GTS
911 CARRERA 4 GTS S-A
911 CARRERA 4 PDK S-A
911 CARRERA 4 S
911 CARRERA 4 S TIP-NIC S
911 CARRERA 4 S-A
911 CARRERA 4 TARGA
911 CARRERA 4 TIPTRONIC
911 CARRERA 4 TIPTRONIC S
911 CARRERA 4S
911 CARRERA 4S AUTO
911 CARRERA 4S PDK S-A
911 CARRERA 4S S-A
911 CARRERA 4S TIP
911 CARRERA 4S TIP S
911 CARRERA AUTO
911 CARRERA CABRIO
911 CARRERA CABRIO AUTO

Check a specific Porsche 911

A model average tells you the pattern. Its own MOT record tells you the car.

Compare within the range

Other Porsche models

Porsche Macan — 89.5% adjusted
Porsche Boxster — 85.7% adjusted
Porsche Cayenne — 85.3% adjusted
Porsche Cayman — 87.2% adjusted
Porsche Taycan — 91.0% unadjusted
Porsche Panamera — 87.8% adjusted
All Porsche models

Similar test volumes

Compare against other makes

Skoda Citigo — 75.1% adjusted, ranked 109
Renault Kangoo — 59.0% adjusted, ranked 257
Mini One — 73.9% adjusted, ranked 122
Fiat Punto — 56.5% adjusted, ranked 261

Common questions

Is the Porsche 911 reliable?: On MOT evidence the Porsche 911 is well above average. It passes 89.5% of tests once age and mileage are accounted for, against a national average of 72.3%. That figure covers 78% of the national age and mileage range, which is enough to quote but not to rank. This measures how often the car meets the MOT standard, not how often it breaks down or what a repair costs.
What is the most common MOT failure on a Porsche 911?: The item recorded most often is "Lambda coefficient outside the default limits or the range specified by the manufacturer", which appears in 11.3% of failed Porsche 911 tests. Because one failed test can list several items, these shares do not add up to 100%.
What do testers most often warn about on a Porsche 911?: The most common advisory is "Tyre tread depth not in accordance with the requirements", noted on 11.2% of all Porsche 911 tests. An advisory is not a failure: it flags something that will likely need attention before the next test.
What mileage does a Porsche 911 usually have at its MOT?: The average odometer reading recorded at test is 57,530 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.
Does a Porsche 911 get harder to pass as it ages?: Yes. At 3 to 5 years old, 95.9% of Porsche 911 tests pass. By fifteen years or more, that falls to 85.4%. Nearly every model follows this pattern, which is why comparing raw pass rates between models is misleading unless age is accounted for.

How this was worked out

Method and limits

Figures come from the DVSA anonymised MOT testing dataset, published under the Open Government Licence. Only class 4 initial tests are counted: retests are excluded so a car appears once, and abandoned tests are excluded entirely. The adjusted rate is directly standardised across twenty-five age and mileage bands and reweighted onto the national distribution, so this model is compared against cars that have lived a similar life rather than against a younger or lighter-used fleet.

An MOT measures whether a car met a legal standard on the day. It is not a breakdown record, a service history or a running-cost estimate, and a pass rate is a property of a fleet rather than a prediction about one car.