2020 Mercedes-Benz SL450

The 2020 Mercedes-Benz SL450 is a luxury roadster known for its elegant design, comfortable ride, and retractable hardtop. The SL450 comes equipped with a 3.0-liter twin-turbocharged V6 engine producing 362 horsepower and 369 lb-ft of torque. All engines were paired with a 9G-TRONIC 9-speed automatic transmission. Some owners praise the car’s smooth ride, powerful engine, and luxurious interior. Common complaints include the complicated infotainment system and the high cost of maintenance and repairs. Also available was the SL550 with a 4.7L V8 making 449 hp and the AMG SL63 with a 5.5L V8 making 577 hp and the AMG SL65 with a 6.0L V12 making 621 hp.

Engine

3.0L Twin-Turbo V6 (SL450)

• Oil Leaks
  • Description/Symptoms: Oil leaks are sometimes reported around the valve cover gaskets or oil filter housing. Visible oil drips under the car and a burning oil smell may be present.
  • Solution: Replacing the leaking gaskets or seals.
  • Estimated Cost to Fix: $300 - $1,000+
  • Recalls: None Found

Transmission

9G-TRONIC 9-Speed Automatic Transmission

• Rough or Delayed Shifting
  • Description/Symptoms: Some owners have reported experiencing rough or delayed shifts, particularly when shifting between lower gears.
  • Solution: In some cases, a software update or transmission adaptation reset can resolve the issue. More severe cases may require valve body replacement or transmission overhaul.
  • Estimated Cost to Fix: $150 (software update) - $5,000+ (transmission overhaul)
  • Recalls: None Found

Suspension

• Air Suspension Issues (if equipped)
  • Description/Symptoms: The optional air suspension system can experience leaks in the air struts or failure of the air compressor, leading to a sagging suspension, uneven ride height, or suspension malfunction warnings.
  • Solution: Replacing the faulty air struts or air compressor.
  • Estimated Cost to Fix: $1,000 - $3,000+ per strut, $800 - $1,500+ for compressor replacement
  • Recalls: None Found

Electrical

• Infotainment System Glitches
  • Description/Symptoms: The COMAND infotainment system can sometimes experience glitches, such as screen freezes, slow response times, or connectivity issues.
  • Solution: Performing a system reset or software update. In some cases, the control unit might need replacement.
  • Estimated Cost to Fix: $0 (reset) - $1,500+ (control unit replacement)
  • Recalls: None Found
• Battery Drain
  • Description/Symptoms: Premature battery drain can occur, especially if the car is not driven frequently.
  • Solution: Inspect the battery and charging system. If no issues are found, ensure all electrical accessories are turned off when the car is not in use or use a trickle charger. If a parasitic draw is found, identify and repair the faulty circuit. Battery replacement.
  • Estimated Cost to Fix: $300 - $500+ (battery replacement), $100 - $500+ (diagnostics), $$$ for parasitic draw repair.
  • Recalls: None Found

Exterior

• Retractable Hardtop Malfunctions
  • Description/Symptoms: The retractable hardtop mechanism can sometimes experience issues, such as getting stuck halfway, failing to open or close completely, or making unusual noises.
  • Solution: Diagnosing and repairing the hydraulic system, sensors, or motors associated with the hardtop mechanism.
  • Estimated Cost to Fix: $500 - $3,000+
  • Recalls: None Found

Interior

• Seat Motor Failure
  • Description/Symptoms: The power seat motors can fail, resulting in the inability to adjust the seat position.
  • Solution: Replacing the faulty seat motor.
  • Estimated Cost to Fix: $300 - $800+
  • Recalls: None Found

Summary

The 2020 Mercedes-Benz SL450, while a luxurious and enjoyable vehicle, can present owners with a range of issues. Most of the issues are common with modern vehicles. Electrical glitches and infotainment system issues are common. Suspension issues, although not occurring with all SL450s, can be very expensive. Most of the other potential problems are relatively minor but can still be inconvenient. Pre-purchase inspections by a qualified mechanic are highly recommended to identify any existing or potential problems.