Unleaded Fuel VS Leaded Fuel

Unleaded

Leaded

Doesn't emit harmful chemicals into the environment.
Contains ethanol components, instead of lead components.
When using unleaded gas it goes through a process called cracking. Cracking is the process of converting harmful gases into harmless gases.

Contains a chemical called Lead Tetraethryl to improve its performance.
Was discovered the amount of lead given off by the cars was making city air very harmful to breathe.
So it's use has been forbidden.