>> 3. Modern diesel engines produce way less smog and noise than the average US car or pickup engine. > Modern diesel engines to not produce less smog than a g

>> 3. Modern diesel engines produce way less smog and noise than the average US car or pickup engine. > Modern diesel engines to not produce less smog than a gasoline engine, they produce more. I think bdfh42 was referring to the existing fleet (including old vehicles) of registered gasoline-powered vehicles. An important point, though, is that newer vehicles tend to be driven more. To wit: the average new passenger vehicle is driven ~15,000 miles per year, whereas the average registered passenger vehicle in general (new+used) is only driven ~12,000 miles per year. The more a vehicle is driven, the more pollution it emits, so it is important for new vehicles to be cleaner than old vehicles.