F1 cars are sport.. they can be as polluting as they like! I think the CO2 from an entire season's racing is only the same as that produced by just one transatlantic Jumbo Jet flight.
On the other hand... flying the teams, cars, equipment and personnel all round the world 20 times a year is a tad more polluting...
But again.. I think they worked it out.. it's miniscule in global terms (cf with everyone leaving their tv on standby for instance).
Ralf S.