MERCEDES S 350 L AMG LN PREM + EXEC D A (2021)
Running costs, reliability data, and common problems from 208 real MOT tests.
Annual Cost
£1,695
£141/month
MOT Pass Rate
91%
Excellent
Road Tax
£195
Flat rate/year
Insurance
Grp 30-42
2925cc Diesel
Great Choice
91% pass rate, £1695/year to run. 9 points above average.
Check a specific MERCEDES S 350 L AMG LN PREM + EXEC D A
Enter a reg plate for full MOT history, mileage check, health score, running costs, and reliability data. Free, instant, no signup.
Annual Running Costs
~40 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.
Get an insurance quote for this MERCEDES S 350 L AMG LN PREM + EXEC D A
Compare quotes and find the best deal
Reliability Verdict
Excellent reliability. Very few MOT failures. That's 9 points above the national average of 82%. It also outperforms the MERCEDES brand average of 87%.
At 5 years old, 91% of MERCEDES S 350 L AMG LN PREM + EXEC D As from 2021 passed their MOT first time in 2026. That's based on 208 tests across the UK. The average mileage at this age is 46,091 miles.
Got a MERCEDES S 350 L AMG LN PREM + EXEC D A you're looking at?
Enter the reg plate to check its specific MOT history, mileage, and health score.
How Does It Compare?
Mileage Analysis
46,091
Average miles
37,000
Expected for age
The average 2021 MERCEDES S 350 L AMG LN PREM + EXEC D A has 46,091 miles on the clock, which is above the expected 37,000 miles for a 5-year-old car. Higher-mileage cars often have more motorway miles, which is generally less harmful than stop-start urban driving.
Looking at a specific MERCEDES S 350 L AMG LN PREM + EXEC D A?
Enter its reg plate for a free check with full MOT history, mileage verification, and predicted costs.
MERCEDES S 350 L AMG LN PREM + EXEC D A by Year
Similar Cars to Consider
Check a Specific Mercedes S 350 l amg ln prem + exec d a
Enter a reg plate to get the full MOT history, health score, and mileage verification.
Upgrade to Premium (£4.99) for stolen, finance, and write-off checks.
About the 2021 MERCEDES S 350 L AMG LN PREM + EXEC D A
The 2021 MERCEDES S 350 L AMG LN PREM + EXEC D A is a large car with a 2925cc diesel engine. 208 of these vehicles were MOT tested in 2026, making it a less common model in the UK market. Among all cars from 2021, the average MOT pass rate is 92%, and this model falls short of that benchmark.
With an average of 46,091 miles at 5 years old, MERCEDES S 350 L AMG LN PREM + EXEC D A owners cover more miles than the average driver.
2021 MERCEDES S 350 L AMG LN PREM + EXEC D A Fuel Costs
The 2925cc diesel engine is on the larger side, so fuel won't be this car's strong point. Expect around 40 mpg in mixed driving, which works out to roughly £1,245 per year at current diesel prices of 148p per litre (based on 7,400 miles per year). Diesel cars of this age should have their DPF (diesel particulate filter) checked, as replacements can be costly.
What does it cost to own a 2021 MERCEDES S 350 L AMG LN PREM + EXEC D A?
Total estimated annual running cost is £1,695 (£141/month), broken down as £1245 fuel, £195 road tax, £55 MOT, and £200 predicted repairs. The low repair estimate reflects the excellent 91% pass rate. These cars rarely fail their MOT, so unexpected bills are less likely.
Buying a Used 2021 MERCEDES S 350 L AMG LN PREM + EXEC D A
At 5 years old, the MERCEDES S 350 L AMG LN PREM + EXEC D A 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
Based on the 2021 MERCEDES S 350 L AMG LN PREM + EXEC D A's fuel type, age, and engine size, these are the most likely problem areas to check.
DPF (Diesel Particulate Filter)
Watch outShort journeys clog the DPF. Replacement costs £1,000-£2,500. Check the DPF warning light and ask about driving patterns.
Turbo Wear
Medium riskDiesel turbos work harder and wear faster. Listen for whining noises and check for oil leaks around the turbo housing.
AdBlue System
Medium riskPost-2015 diesels use AdBlue for emissions. Sensor failures and tank heater issues are common. Budget £200-£500 for repairs.
EGR Valve
Low riskExhaust Gas Recirculation valves clog with carbon deposits, causing rough running and poor economy. Cleaning costs £150-£300, replacement £300-£600.
Dual Mass Flywheel
Medium riskLarger diesel engines put extra strain on the dual mass flywheel. Listen for rattling at idle. Replacement with clutch is £800-£1,500.
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 S 350 L AMG LN PREM + EXEC D A stacks up against similar cars for annual running costs, insurance, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Insurance | Total/yr |
|---|---|---|---|---|---|
| MERCEDES S 350 L AMG LN PREM + EXEC D A(2021) | 91% | £1245 | £195 | Grp 30-42 | £1695 |
| MERCEDES E(2019) | 90% | £1245 | £190 | Grp 30-42 | £1690-£5 |
| FORD RANGER(2019) | 87% | £1245 | £190 | Grp 35-50 | £1840+£145 |
| AUDI Q5(2019) | 93% | £1245 | £190 | Grp 30-42 | £1690-£5 |
| AUDI A5(2019) | 90% | £1245 | £190 | Grp 30-42 | £1690-£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
MERCEDES E
2019 · 2925cc Diesel
FORD RANGER
2019 · 3198cc Diesel
AUDI Q5
2019 · 2967cc Diesel
Related Guides
In-depth articles relevant to the Mercedes S 350 l amg ln prem + exec d a.
Petrol vs Diesel in 2026: Which Actually Costs Less to Own?
8 min read
Buying GuideCars That Lose Value Fastest: Models to Avoid for Depreciation
8 min read
Running CostsCheapest Cars to Run in 2026: Real Data from 19.8 Million MOT Tests
9 min read
Buying GuideFord Fiesta Common Problems (2026): What to Check Before Buying
13 min read
ReliabilityFord Puma Problems: 7 Issues Owners Report (2026)
13 min read
Check a specific MERCEDES S 350 L AMG LN PREM + EXEC D A
Enter the reg to see its MOT history, mileage check, and predicted costs.
Premium History Check
Buying a MERCEDES S 350 L AMG LN PREM + EXEC D A? Our premium check covers:
- Stolen check (PNC)
- Outstanding finance
- Write-off history (Cat A/B/N/S)
- Previous owners count
Competitors charge £10-£20 for the same data