Porsche Cayman vs Mercedes-Benz SL-Class
The Porsche Cayman is the more efficient of the two: it reaches 25 mpg combined versus 23 mpg for the Mercedes-Benz SL-Class, a 2 mpg advantage and costs about $250 less per year to fuel.
Across 5 measured categories, the Porsche Cayman leads in 5. Figures are EPA test data, not manufacturer claims.
2015–2027
Mercedes-Benz SL-Class
Two Seaters · 40 configurations
Head-to-head specifications
| Metric | Porsche Cayman | Mercedes-Benz SL-Class |
|---|---|---|
| Best combined MPG | 25 mpg ✓ | 23 mpg |
| Best city MPG | 22 mpg ✓ | 21 mpg |
| Best highway MPG | 31 mpg ✓ | 28 mpg |
| Lowest annual fuel costEPA estimate at 15,000 miles per year | $3,050 ✓ | $3,300 |
| Lowest CO2 output | 352 g/mi ✓ | 379 g/mi |
| Engines offered | SIDI | SIDI, SIDI; Mild Hybrid, SIDI; PHEV, 6.0 |
| Transmissions | Manual 6-spd, Automatic (AM-S7) | Automatic 9-spd, Automatic 7-spd |
| Drivetrains | Rear-Wheel Drive | All-Wheel Drive, Rear-Wheel Drive |
| Fuel types | Premium | Premium, Premium and Electricity |
| EPA class | Two Seaters | Two Seaters |
| Years covered | 2015–2020 | 2015–2027 |
| Configurations on record | 35 | 40 |
Source: EPA fuel economy records via fueleconomy.gov. Best-case values across all recorded configurations for each model.
Cayman vs SL-Class: common questions
Which is better on gas, the Porsche Cayman or the Mercedes-Benz SL-Class?
The Porsche Cayman is the more efficient of the two: it reaches 25 mpg combined versus 23 mpg for the Mercedes-Benz SL-Class, a 2 mpg advantage and costs about $250 less per year to fuel.
Which costs less to run per year?
By EPA estimates at 15,000 miles a year, the Porsche Cayman runs about $3,050 a year in fuel at its most efficient configuration, versus about $3,300 for the Mercedes-Benz SL-Class — a difference of roughly $250 per year.
What engines do the Cayman and SL-Class offer?
Porsche Cayman: SIDI. Mercedes-Benz SL-Class: SIDI, SIDI; Mild Hybrid, SIDI; PHEV, 6.0.
Are they in the same vehicle class?
Yes — the EPA classifies both the Porsche Cayman and the Mercedes-Benz SL-Class as Two Seaters, so they compete directly.
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