Emissions controls do in fact go bad. Catalytic converters clog and fail, evap canisters, EGR valves all can stop working, exhaust connections rust and break, ignition problems and so on. A modern car can pollute just as much as a car with no emissions controls even if perfectly maintained so while modern emissions controls are effective at eliminating upwards of 90%+ of the 'pollution' if those controls fail then one car is polluting as much as 90+ other vehicles.
Extrapolate and do the math. If thousands, hundreds of thousands, millions (CA 38 million, US population ~320 million) weren't required to check and make sure their vehicle's systems are still operating properly...
If you are selfish, don't have children or young relatives, don't care about the future of Earth and life as we know it or just hate smart people who actually do research on the subject then continue with the false-equivalence Idiocracy-style science denying fact hating bull**** nonsense.
"Slate contributor Eric Holthaus said that he had foresworn flying because of its disproportionate climactic impact. In his piece describing why he took a 28-hour bus ride from Wisconsin to Atlanta, he noted that the amount of emissions associated with driving that distance in a Honda Civic (1,386 pounds of carbon dioxide) was roughly equal to the amount of emissions he would have caused in flying that distance (1,587). Note, of course, that the 2012 Honda Civic gets 39 miles per gallon on the highway, where most of that driving would take place—far above average. Sivak’s study points out that the average light-duty vehicle on the road in the U.S. gets about 21.5 miles per gallon. His study suggests that vehicles would have to get more than 33.8 miles per gallon in order to be less fuel-intensive than air travel. Holthaus crossed that threshold by incurring a huge personal inconvenience,"
Driving vs. flying: Which is more harmful to the environment?
Its often almost the same if the driver is carpooling (ie riding a bus), if you're driving around all smug in your own personal car by yourself then the plane will actually beat out the automobile regularly in efficiency and pollution, especially if you're driving carbureted junk. If you really care you'd stop whining and figure out how to put a catalytic on jet propulsion instead of making useless comparisons that you shouldn't have to smog check your car because airplanes don't have to.
Knew this thread was going to be nothing but stupid whiny bullcrap.