Been using Shell gas since I purchased ( Aug. 2011 ) the CT. From time to time I have also smelled that " rotten egg " smell, so don't think gas is the answer. Haven't had it now for several months so not sure what it is.
I've been using cheap gas from Costco or Superstore (grocery store in Canada) since I bought our CT a year ago. About a month ago I started having a "rotten egg" smell coming from my car on quite a regular basis for about a month straight. After googling the problem, cheap gas can give off a sulfur smell. I've switched to Shell V Power for my past 4 tanks of gas... and I haven't had the smell since. Maybe it'll come back... maybe this isn't the fix... but it seems to be doing the trick so far.