Owner complaints, recalls, fuel economy and safety ratings from public NHTSA and EPA data, updated Oct 17, 2026.
Fuel economy
17–21 mpgcombined; city 14–19, highway 22–26; every version of this model year
Five years of fuel
$19,160–$23,670U.S. average; Ohio $18,060–$22,310 at local prices; every version of this model year; fuel only, not other costs of owning it; 15,000 miles a year, at EIA fuel prices for the week of Oct 12, 2026
NHTSA overall safety rating
Not ratedNHTSA has no overall rating for this year
Owners have filed 3 complaints with NHTSA about the 2009 SLK-Class. These are unverified owner reports, counted by the part of the car they name; one complaint can name several parts. Counts aren't adjusted for how many were sold, so they don't show how reliable a car is.
Complaints by part of the car
Part
Complaints
Crashes
Fires
Injuries
Steering
2
0
0
0
Electrical system
1
0
0
0
Electronic stability control (ESC)
1
0
0
0
Service brakes
1
0
0
0
Tires
1
0
0
0
Unknown or other
1
0
0
0
Complaints by model year
Newer years have had less time to collect complaints, and counts aren't adjusted for sales, so a shorter bar doesn't mean a more reliable year.
NHTSA lists 1 recall campaign for the 2009 SLK-Class over its history. Campaigns are matched by model and year, so each one may apply to a given car, and its repair may already be done: check a VIN on NHTSA's recall lookup for the open recalls on that exact car.
MERCEDES-BENZ IS RECALLING MY 2006-2008 M-CLASS, R-CLASS, MY 2005-2009 SLK-CLASS, MY 2005-2008 C-CLASS, MY 2003-2004 AND 2006-2008 CLK-CLASS, MY 2003-2008 E-CLASS, MY 2004 AND 2008 CL-CLASS, MY 2008 CLS-CLASS, MY 2004 AND 2007-2008 S-CLASS, MY 2003 G-CLASS, AND MY 2003-2004, 2006 AND 2009 SL-CLASS VEHICLES. A SOFTWARE CALIBRATION NUMBER (SCN) CODING RECEIVED ON THE AFFECTED VEHICLES DURING A RECENT WORKSHOP VISIT WAS INCORRECT. DEPENDING ON THE MODEL YEAR AND MODEL AFFECTED, THE RESULTS OF AN INCORRECT SCN CODING CAN AFFECT A NUMBER OF VEHICLE SAFETY AND EMISSION FUNCTIONS INCLUDING THE FOLLOWING TYPES OF FUNCTIONS: (1) THE FUEL GAUGE READINGS MAY BE INCORRECT; (2) A STUCK FUEL-LEVEL SENSOR MAY NOT BE DISPLAYED IN THE INSTRUMENT CLUSTER; (3) THE OBD SYSTEM MAY CAUSE THE CHECK ENGINE LIGHT TO ILLUMINATE INCORRECTLY; AND, (4) THE SPEEDOMETER MAY BE OUT OF TOLERANCE.
Risk: IN THE EVENT OF A VEHICLE CRASH, THE ELECTRICAL FUEL PUMP MAY NOT RECEIVE A CRASH SIGNAL THAT IS REQUIRED FOR THE FUEL PUMP TO DISCONNECT AND PREVENT FUTURE FUEL DELIVERY AS DESIGNED.
Remedy: DEALERS WILL RECODE THE SCN FREE OF CHARGE. THE RECALL BEGAN ON AUGUST 30, 2008. OWNERS MAY CONTACT MERCEDES-BENZ AT 1-800-367-6372.
Carmakers sent NHTSA 71 service bulletins and notices that cover the 2009 SLK-Class, the latest on Sep 22, 2026. They tell dealers how to fix known issues.
The parts they mention most: exterior lighting (14), electrical system (8), equipment (8), engine and engine cooling (7), power train (7).
NHTSA hasn't opened a defect investigation that covers this model year.
Maintenance
Oil
The owner's manual gives the oil and how often to change it. We show oil facts only once we've checked them against the manual, and we haven't yet for the 2009 SLK-Class.
NHTSA manufacturer communications, file of Oct 17, 2026
NHTSA defect investigations, file of Oct 17, 2026
NHTSA 5-Star Safety Ratings, file of Aug 7, 2026
U.S. Energy Information Administration, file of Oct 12, 2026
Fuel cost: EPA mpg with fuel prices for the week of Oct 12, 2026 and electricity prices for Jul 2026. Source: U.S. Energy Information Administration (Oct 2026). Complaints are unverified reports owners filed with NHTSA. About the data