Never Try To Save On Maintenance
Train Yourself To Drive Economically
Avoid using Your Car Unnecessarily
Fuel and Emission Systems
Once the gas is burnt in the engine the emission system is responsible for controlling what and how is released into the atmosphere.
In summation, if you want a car that's as echo friendly as it can be keep it well maintained, use it only when you really need to and drive it in a responsible, economical way.