ojis, I see where you're coming from but I was trying to make the very simplest of points:
Supercars are rare, exclusive and special; the low number of them relative to even the most environmentally efficient mass-market cars out there means that their total contribution to greenhouse gasses is a mere fraction.
Of course, saving the environment and the planet are paramount considerations but let's target the really big contributors to global warming and environmental pollution and not a merry little band of supercars. Leave them supercars be - I say...
So, the heading of top ten most polluting cars is dreadfully inaccurate.