The National Highway Traffic Safety Administration (NHTSA) is investigating certain 2003-2006 Mercedes Benz E55 AMG sedans and wagons for potential gas leaks. The NHTSA has received over 20 reports from owners who complained about the smell of gasoline inside and outside the vehicle. In some cases, a visible fuel leak was noticed from the fuel sending unit at the top of the fuel tank, underneath the cushion in the rear seat. Several reports suggest the leakage may be related to a March, 2008 emissions recall conducted by Mercedes Benz (Emissions Recall Campaign # 2008-020001) which involved potential cracking of the fuel filter module in vehicles exposed to high ambient temperatures. If the investigation leads to a recall, over 8,000 vehicles could be affected.