Hydrocarbon, carbon dioxide, and nitrogen oxide
emissions from gasoline fueled cars can be reduced by
50 percent or more from uncontrolled levels through
engine modifications, at a cost of about U.S.$130 per
car. Further reductions to the 80 to 90 percent level are
possible with three-way catalysts and electronic engine
control systems at a cost of about U.S.$600 - $800 per
car. Excessive hydrocarbon and particulate emissions
from two-stroke motorcycles and three-wheelers can be
lowered by 50 to 90 percent through engine modifications
at a cost of U.S.$60 - $80 per vehicle. For diesel engines,
nitrogen oxide and hydrocarbon emissions can
be reduced by 30 to 60 percent and particulate matter
emissions by 70 to 80 percent at a cost less than
U.S.$1,500 per heavy-duty engine