car problems

i have a strong metallic rotten egg smell in my car when it heats up.  i can smell it at traffic lights or when i open the air vents.  very unpleasant.  everyone thinks it's the catalytic converter (i have no idea if that is correct spelling).  i saw my mechanic yesterday who thought it was due to the bit on top of the engine that has oil and plugs in it as it's been leaking for a while.  well, he changed the seal and cleaned it up.  but, on the way home i got the smell again.  maybe it is the catalytic thingy.  i hate having car problems.  the expense alone is enough of a worry.  i'll ring him this afternoon and tell him what's going on.  i must say that the car felt heavy and a bit sluggish and now it's zippy again so obviously the seal thing was making a difference.  of course, when i retire in april i'm going to upgrade to a car with power steering, 4 doors and a cup holder.  can't wait

i've been thinking about the hyundai i3 or something like that but everyone says it's not a good car.  i have no idea.  my mechanic suggested a toyota corollla.  i'll check it out on carsales.