Porsche 718 Cayman GT4 (2021)
Estimated running costs and MOT pass rates from 133 MOT tests in 2024.
Annual Cost
£2,413
£201/month
MOT Pass Rate
95%
Excellent
Road Tax
£200
Standard rate/year
Est. Insurance
Grp 35-50
3995cc Petrol
Great Choice
95% pass rate, £2,413/year to run. 13 points above average.
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Annual Running Costs
~30 mpg
Standard rate (from April 2017)
Low estimate due to excellent reliability
Estimates based on 7,400 miles/year (UK average), petrol at 174.57p a litre (GOV.UK weekly average, week of 19 October 2026), GOV.UK road tax rates and repair likelihood from MOT data. Insurance not included. Cars registered from April 2017 pay the £200 standard rate, plus £440 a year for five years (from the second year) if they cost over £40,000 new (over £50,000 for electric cars).
Reliability Verdict
Excellent reliability. Very few MOT failures. That's 13 points above the average of 82% across all models in our data.
95% of MOT tests on Porsche 718 Cayman GT4s from 2021 ended in a pass in 2024, when they were about 3 years old. That's based on 133 tests across the UK, retests included. The average mileage recorded at those tests was 9,270 miles.
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How Does It Compare?
Mileage Analysis
9,270
Average miles
22,200
Expected for age
The average 2021 Porsche 718 Cayman GT4 had 9,270 miles on the clock at its 2024 MOT, which is significantly below the expected 22,200 miles for a 3-year-old car. Low-mileage examples may have spent time sitting unused, so check for issues like corroded brakes or perished rubber seals.
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Best Year to Buy?
Of the years with at least 100 tests, the 2020 model has the highest MOT pass rate at 98%, while the 2021 model has the lowest at 95%. Consider a different year if reliability is a priority. Newer cars usually pass more often simply because they are younger, so compare years of a similar age.
Porsche 718 Cayman GT4 by Year
Similar Cars to Consider
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About the 2021 Porsche 718 Cayman GT4
The 2021 Porsche 718 Cayman GT4 is a luxury car. Our records list a 3995cc petrol engine, though engines vary between versions. 133 MOT tests were recorded on this model in 2024, making it a rare model on UK roads. Among all models from 2021, the average MOT pass rate is 92%, and this model beats that benchmark.
With an average of 9,270 miles recorded at its 2024 MOT tests, Porsche 718 Cayman GT4 owners tend to use this car less than the typical driver. Very low mileage could mean the car has been garaged or used only for short trips, which can cause its own issues like battery drain and moisture buildup.
2021 Porsche 718 Cayman GT4 Fuel Costs
The 3995cc petrol engine is on the larger side, so fuel won't be this car's strong point. Expect around 30 mpg in mixed driving, which works out to roughly £1,958 per year with petrol at 174.57p per litre (GOV.UK weekly average, week of 19 October 2026; based on 7,400 miles per year).
What does it cost to own a 2021 Porsche 718 Cayman GT4?
Total estimated annual running cost is £2,413 (£201/month), broken down as £1,958 fuel, £200 road tax, £55 MOT, and £200 predicted repairs. The low repair estimate reflects the excellent 95% pass rate. These cars rarely fail their MOT, so unexpected bills are less likely.
Porsche 718 Cayman GT4 Reliability Trend
The Porsche 718 Cayman GT4 has maintained consistent MOT pass rates across model years, varying by only 1 percentage point.
Buying a Used 2021 Porsche 718 Cayman GT4
At 5 years old, the Porsche 718 Cayman GT4 offers good value with plenty of life remaining. Most manufacturer warranties will have expired, so a pre-purchase inspection is worth the cost.
Common Issues to Watch For
These are typical issues for cars of this age, fuel type and engine size, not faults recorded on this model's MOT tests. Use them as a checklist when you view one.
Oil Consumption
Low riskLarger petrol engines can develop higher oil consumption as they age. Check the oil level and look for blue smoke from the exhaust.
Service History
Low riskAlways request a full service history. Regular servicing is the single best indicator of how well a car has been maintained, regardless of mileage.
Running Costs Compared
How the 2021 Porsche 718 Cayman GT4 stacks up against similar cars for estimated annual running costs, insurance group, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Est. Ins. Group | Total/yr |
|---|---|---|---|---|---|
| Porsche 718 Cayman GT4(2021) | 95% | £1,958 | £200 | Grp 35-50 | £2,413 |
| Mercedes C(2019) | 91% | £1,958 | £200 | Grp 35-50 | £2,413same |
| Porsche Cayenne(2019) | 95% | £1,958 | £200 | Grp 35-50 | £2,413same |
| Porsche 911(2019) | 97% | £1,958 | £200 | Grp 35-50 | £2,413same |
| Audi A6(2020) | 94% | £1,958 | £200 | Grp 35-50 | £2,413same |
Estimates based on 7,400 miles/year, GOV.UK average pump prices for the week of 19 October 2026, GOV.UK road tax rates and MOT data. Insurance groups are our rough estimate from engine size, not official groups. Actual costs vary by driver, location, and usage.
Questions about the 2021 Porsche 718 Cayman GT4
Is the 2021 Porsche 718 Cayman GT4 reliable?
Excellent reliability. Very few MOT failures. 95% of MOT tests on 2021 Porsche 718 Cayman GT4s ended in a pass, from 133 tests (DVSA MOT data for tests in 2024, retests included). That's 13 points above the average of 82% across all models in the same data.
How much does a 2021 Porsche 718 Cayman GT4 cost to run?
Our estimate is £2,413 a year (£201 a month): £1,958 fuel, £200 road tax, £55 MOT and £200 predicted repairs, based on 7,400 miles a year. Insurance is not included.
What is the MOT pass rate for a 2021 Porsche 718 Cayman GT4?
95% of 133 MOT tests on the 2021 Porsche 718 Cayman GT4 ended in a pass (DVSA MOT data for tests in 2024, retests included). That ranks it 953rd of 3,336 models first registered in 2021 (top half).
Which year Porsche 718 Cayman GT4 has the best MOT pass rate?
Of the years with at least 100 tests, the 2020 Porsche 718 Cayman GT4 has the highest MOT pass rate at 98% and the 2021 the lowest at 95%. Newer cars usually pass more often simply because they are younger and have done fewer miles.
What is the average mileage for a 2021 Porsche 718 Cayman GT4?
The average mileage recorded at MOT tests on the 2021 Porsche 718 Cayman GT4 is 9,270 miles, which is significantly below the expected 22,200 miles for a 3-year-old car. Low-mileage examples may have spent time sitting unused, so check for issues like corroded brakes or perished rubber seals.
Related Porsche Models
Explore other Porsche cars or similar models in the same category.
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Mercedes C
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Porsche Cayenne
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