This wasn't sarcastic at all—any driver of a car is far more dangerous than one in a plane. 9/11 is essentially meaningless in the shadow of auto deaths (to provide a direct comparison). I can't get a firm number on number of plane fatalities in the US (or auto fatalities worldwide), but 9/11 alone would amount to about only 0.04% of total vehicle fatalities in the US since 2000.