[sdljfjafsd]

Practically this incorrect. When a car is in single or double occupancy (which is majority of cases) it will pollute more than a motorcycle one. Yes, a filled bus or car might be more efficient, but the average utilization on an auto is very low since most people drive them alone.

[MagnumOpus]

You might be talking CO2 emissions where a car emits more than a bike.

Pollution is a different matter though. Even the big 4-stroke tourers have worse emission control than cars; the 2-stroke motorbikes are exponentially worse in SOx/NOx/CO/particulate emissions (which hurt your lungs rather than the climate).