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Porsche 911 reliability, MPG and running costs

Figures updated

The Porsche 911 is a sports car. In 2024 MOT tests it scored 261 for reliability (100 is average), ranking 7 of 442, and 10.0% failed first time against a UK average of 28.5%. Its most common MOT failure is catalyst emissions (1.0% of tests).

261Well above average

Ranked 7 of 442 cars in the 2024 MOT Reliability League, and 1 of 7 sports cars

In 2024, 34,721 Porsche 911s aged 3 to 20 had an MOT and 10.0% failed first time (UK average 28.5%). Taking age and mileage into account, the Porsche 911 is 62% less likely to fail than the average car of the same age and mileage. At the first MOT, at three years old, 5.5% failed (UK 12.7%).

First-time fail rate

10.0%

UK 28.5%

Fail rate at 3 years

5.5%

UK 12.7%

Average miles a year

3,900

Typical age at test: 12 years

Porsche 911 MOT failure rate by age

0%10%20%30%40%50%36912151820UK average 43%911 18%

Most common Porsche 911 MOT faults

  1. Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits1.0% of tests
  2. Headlamp aim: too high0.9% of tests
  3. Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt0.9% of tests
  4. Condition: has a cut in excess of the requirements deep enough to reach the ply or cords0.9% of tests
  5. Condition: has ply or cords exposed0.8% of tests
  6. Tread depth: tread depth below requirements of 1.6mm0.7% of tests

What the Porsche 911 fails on

AreaTests failingvs similar cars
Lights and electrics2.8%▼ 73% less often
Tyres2.7%▼ 45% less often
Exhaust and emissions1.6%▼ 44% less often
Brakes1.4%▼ 77% less often
Body and structure1.3%▼ 62% less often
Suspension1.1%▼ 86% less often
Visibility1.0%▼ 78% less often
Steering0.3%▼ 82% less often
Seat belts and airbags0.2%▼ 75% less often
Wheels0.1%▼ 60% less often

What MPG does the Porsche 911 do?

Official economy for the Porsche 911 ranges from 20.3 to 38.2mpg across the 309 versions listed by the Vehicle Certification Agency (2004–2025). A typical petrol version manages 31.7mpg. Expect 10–15% less in real-world driving.

Work out a journey's fuel cost

How much is road tax on a Porsche 911?

Any Porsche 911 first registered from April 2017 pays the standard rate of £200 a year after its first year (2026/27 rates). A Porsche 911 registered between March 2001 and March 2017 is taxed on its CO2: £225 to £790 a year.

Work out tax for a specific car

Porsche 911 specs and running costs

Official figures for 309 versions sold in the UK between 2004 and 2025.

Fuel types

Hybrid, Petrol

Official economy

20.3–38.2 mpg

CO2

141–339 g/km

Power

394–541 PS

VersionFuelEconomyCO2Car taxCompany car tax
911 911 Carrera 4 GTS Cabriolet541 PS · A8 · listed 2025Hybrid25.9 mpg247g£20037%
911 911 Targa 4 GTS541 PS · A8 · listed 2025Hybrid25.9 mpg247g£20037%
911 911 Carrera 4 GTS541 PS · A8 · listed 2025Hybrid25.8 mpg248g£20037%
911 911 Spirit 70541 PS · A8 · listed 2025Hybrid26.2 mpg245g£20037%
911 911 Carrera GTS Cabriolet541 PS · A8 · listed 2025Hybrid26.1 mpg246g£20037%
911 911 Carrera GTS541 PS · A8 · listed 2025Hybrid25.9 mpg247g£20037%
911 911 Carrera Cabriolet394 PS · A8 · listed 2025Petrol27.2 mpg237g£20037%
911 911 Carrera T Cabriolet394 PS · M6 · listed 2025Petrol26.1 mpg245g£20037%
911 911 Carrera394 PS · A8 · listed 2025Petrol26.9 mpg239g£20037%
911 911 Carrera T394 PS · M6 · listed 2025Petrol26 mpg246g£20037%
911 911 Carrera 4S Cabriolet480 PS · A8 · listed 2025Petrol26 mpg247g£20037%
911 911 Targa 4S480 PS · A8 · listed 2025Petrol25.8 mpg248g£20037%
911 911 Carrera 4S480 PS · A8 · listed 2025Petrol25.8 mpg248g£20037%
911 911 Carrera S Cabriolet480 PS · A8 · listed 2025Petrol26.7 mpg240g£20037%
911 911 Carrera S480 PS · A8 · listed 2025Petrol26.4 mpg243g£20037%

Economy and CO2 are official WLTP figures. Car tax is the yearly rate at current rates for a car first registered in the year listed, before any expensive car supplement. Company car tax is the 2026/27 benefit-in-kind rate. Showing the 15 most recent of 309 versions.

What a Porsche 911 costs to fuel

  • petrol, typical official 31.7mpg…

Official figures are usually 10–15% better than real-world driving.

Work out a journey in a Porsche 911

Buying a used Porsche 911?

Check the MOT history of the exact car: every result, advisory and mileage reading, free.

Compare the Porsche 911 with other sports cars

Reliability, economy, car tax and running costs side by side.

Other Porsche models

Frequently asked questions

›Is the Porsche 911 reliable?

Its MOT record is better than average: the Porsche 911 is 62% less likely to fail than the average car of the same age and mileage, with a reliability score of 261 in our 2024 league (100 is average).

›What are common problems with the Porsche 911?

The most common MOT fault is “Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits”, found in 1.0% of tests.

›What MPG does the Porsche 911 do?

Official economy for the Porsche 911 ranges from 20.3 to 38.2mpg across the 309 versions listed by the Vehicle Certification Agency (2004–2025). A typical petrol version manages 31.7mpg. Expect 10–15% less in real-world driving.

›How much is road tax on a Porsche 911?

Any Porsche 911 first registered from April 2017 pays the standard rate of £200 a year after its first year (2026/27 rates). A Porsche 911 registered between March 2001 and March 2017 is taxed on its CO2: £225 to £790 a year.

›How many Porsche 911s fail their MOT?

10.0% of Porsche 911s aged 3 to 20 failed their MOT first time in 2024, and 5.5% failed at their first MOT.

Sources: DVSA anonymised MOT tests 2024, all versions of the Porsche 911 combined (Open Government Licence v3.0); official economy and CO2 from Vehicle Certification Agency data, © Crown copyright. VCA cannot accept liability for its accuracy. How we calculate the league.