Other Fuel System Tank Filling/charging problems of the 2006 Mercedes Benz E55

I own two mercedes E55 vehicles. One is 2005, one is 2006. On the 2005 I have had what has become a common symptom of fuel smell first outside the car (especially after filling the tank completely), which migrates to inside the car as the problem worsens. I believe a recall compaign was performed on the car in 2011 to address this issue. The problem returned. The car is obviously out of warranty and has had the issue addressed a few times now. As the original owner, I have had first hand experience of the issue over the course of 9 years. I did not think too much of it at the time, except now that I have another 2006 E55. . . Virtually identical. . . Exact same thing is happening. The 2006 was purchased used in July of 2013. I complained to the used car dealer about the issue (it came with a 6 month warranty) and they said it was possibly a leaking o-ring on a spark plug. The fuel smell remained after the repair however, very strong when tank filled or the car on an incline. . . Especially on hot days. Only after searching the internet did I find that many others had the same experience. . . And I was 2 for 2 on my cars. Same models, same symptoms. The 2006 unit is far worse, however and may have never had the original recall performed. I pulled the back seats and inspected the fuel areas. . . And sure enough small puddles of gas and stains from previous puddles. The smell is so strong now I avoid using the car. When you have a single car with a singular problem you don't suspect much. When you read about others with a similar issue, your suspicions may raise a bit. However, I promise you when you buy another identical car and it has the exact same overwhelming problem, that's when you wake up. The fuel smell is so strong, I have not had a single occupant not notice in the last 3 months. I'm parking the car until I can figure out a way to get it resolved.