NHTSA said it is "closing this investigation based on the manufacturer's extend warranty of the affected fuel system components and in consideration that the nature of the leaks does not appear to present an unreasonable risk to motor vehicle safety."

NHTSA said when the tank is full, fuel can slowly weep or seep from micro-cracks in these components and may collect in cavities on top of the filter/sender, pump, or tank. "Contrary to complainant's allegations that fuel entered the inside of their vehicle under the rear seat bench, neither (NHTSA) nor Mercedes found a plausible way for this to occur," NHTSA said. "The fuel tank is located outside of the passenger compartment, attached to the underside of the vehicle. The service access ports for the fuel filter/sender (driver's side) and fuel pump (passenger's side) are located under the rear seat bench, covered by a steel plate, sealed and bolted to the vehicle floor."