MERCEDES SL 400 GRAND EDITION PREMIUM A (2021)
Running costs, reliability data, and common problems from 41 real MOT tests.
Annual Cost
£2,042
£170/month
MOT Pass Rate
100%
Excellent
Road Tax
£195
Flat rate/year
Insurance
Grp 30-42
2996cc Petrol
Great Choice
100% pass rate, £2042/year to run. 18 points above average.
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Annual Running Costs
~30 mpg
Flat rate (post-2017)
Low estimate due to excellent reliability
Based on 7,400 miles/year (UK average), current fuel prices, and repair likelihood from MOT data. Insurance not included.
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Reliability Verdict
Excellent reliability. Very few MOT failures. That's 18 points above the national average of 82%. It also outperforms the MERCEDES brand average of 87%.
At 5 years old, 100% of MERCEDES SL 400 GRAND EDITION PREMIUM As from 2021 passed their MOT first time in 2026. That's based on 41 tests across the UK. The average mileage at this age is 13,184 miles.
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How Does It Compare?
Mileage Analysis
13,184
Average miles
37,000
Expected for age
The average 2021 MERCEDES SL 400 GRAND EDITION PREMIUM A has 13,184 miles on the clock, which is significantly below the expected 37,000 miles for a 5-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?
The most reliable year is the 2020 model with a 97% MOT pass rate, while the 2019 model has the lowest at 97%. The 2021 sits between the two at 100%.
MERCEDES SL 400 GRAND EDITION PREMIUM A by Year
Similar Cars to Consider
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About the 2021 MERCEDES SL 400 GRAND EDITION PREMIUM A
The 2021 MERCEDES SL 400 GRAND EDITION PREMIUM A is a large car with a 2996cc petrol engine. 41 of these vehicles were MOT tested in 2026, making it a rare model on UK roads. It ranks in the top 2% of all 2021 cars for reliability.
With an average of 13,184 miles at 5 years old, MERCEDES SL 400 GRAND EDITION PREMIUM A 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 MERCEDES SL 400 GRAND EDITION PREMIUM A Fuel Costs
The 2996cc 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 £1,592 per year at current petrol prices of 142p per litre (based on 7,400 miles per year).
What does it cost to own a 2021 MERCEDES SL 400 GRAND EDITION PREMIUM A?
Total estimated annual running cost is £2,042 (£170/month), broken down as £1592 fuel, £195 road tax, £55 MOT, and £200 predicted repairs. The low repair estimate reflects the excellent 100% pass rate. These cars rarely fail their MOT, so unexpected bills are less likely.
Buying a Used 2021 MERCEDES SL 400 GRAND EDITION PREMIUM A
At 5 years old, the MERCEDES SL 400 GRAND EDITION PREMIUM A offers good value with plenty of life remaining. Most manufacturer warranties will have expired, so a pre-purchase inspection is worth the cost. If you're flexible on year, the 2020 model has the highest pass rate at 97%. Note: with only 41 tests in our data, these figures should be treated as indicative rather than definitive.
Common Issues to Watch For
Based on the 2021 MERCEDES SL 400 GRAND EDITION PREMIUM A's fuel type, age, and engine size, these are the most likely problem areas to check.
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 MERCEDES SL 400 GRAND EDITION PREMIUM A stacks up against similar cars for annual running costs, insurance, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Insurance | Total/yr |
|---|---|---|---|---|---|
| MERCEDES SL 400 GRAND EDITION PREMIUM A(2021) | 100% | £1592 | £195 | Grp 30-42 | £2042 |
| BMW 5 SERIES(2019) | 92% | £1592 | £190 | Grp 30-42 | £2037-£5 |
| BMW X3(2019) | 92% | £1592 | £190 | Grp 30-42 | £2037-£5 |
| MERCEDES GLC(2019) | 93% | £1592 | £190 | Grp 30-42 | £2037-£5 |
| BMW X5(2019) | 92% | £1592 | £190 | Grp 30-42 | £2037-£5 |
Estimates based on 7,400 miles/year, current fuel prices, and MOT data. Insurance groups are indicative. Actual costs vary by driver, location, and usage.
Related Mercedes Models
Explore other Mercedes cars or similar models in the same category.
MERCEDES A
2019 · 1461cc Diesel
MERCEDES C
2017 · 1991cc Hybrid
MERCEDES A-CLASS
2017 · 1461cc Diesel
BMW 5 SERIES
2019 · 2998cc Petrol
BMW X3
2019 · 2998cc Petrol
MERCEDES GLC
2019 · 2996cc Petrol
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