Derays550

I recently purchased my 09 s550, it's sweet to say the least. However when I got it on delivery day I bring it home park it in the garage and once I close garage door I smell gas fumes! I took it to Benz and they fix it somewhat. I no longer smell gas in the garage but if I accelerate hard to 80MPH I get gas fumes in the cabin. I have the sun roof cracked open (vented) when I smell it. As long as the roof is closed I don't smell anything.

Hopefully someone has had this issue before and can at least let me know what they did to fix this.

Thanks for the help.