Used vehicle engines Automobile exhaust is the most problematic substances from vehicles are important. Carbon monoxide, hydrocarbons, oxides of nitrogen And brimstone About 55% of the hydrocarbons coming out the exhaust pipe from 25% out of the crankshaft and the other 20% is due to the volatility in the carburetor. And fuel tanks Oxides of nitrogen is Nitric oxide (NO), nitrogen dioxide (NO2) and nitrous oxide (N2O) almost entirely out of the tailpipe. Directly toxic to humans In addition, leaded gasoline has increased the amount of lead in the air, super well.