Exponential is a term to refer to the change in just one variable, usually over time when we are talking of growth. You can't say that something produces "exponentially" more emissions than something else. Here, you would have to go back to using simple multiples for such comparisons.Get rid of houses, factories, hospitals, schools etc. as they contribute far more (exponentially) than vehicles.
I'm also intrigued to know which, in your opinion, is more vital to society's survival, hospitals and schools, or aeroplanes and 4x4s. And can you justify it too please.


.