I came across something online that claimed that diesel buses emit 200x the pollution of a normal passenger car. I looked into this, read some studies, and it’s not true.
The average vehicle on the road emits ~1# of CO2/mile (it’s higher for light trucks, lower for cars, but it works out quite well). I looked up some testing data, and a late-90s diesel bus on low-sulfur fuel (no trap, none of the new cool technology) puts out ~6.4# CO2/mile.
So an older diesel bus = about six cars, CO2-wise.
– There’s a lot of variance in how much pollution an individual bus generates
– This doesn’t account for the relative harm of the pollution generated by the different vehicles, and there’s a case to be made that the buses should account for non-CO2 products
But as a range… there’s just no way it’s 1-to-200.