1. Regulatory testing procedures

The pollutants emitted by vehicles, and by internal combustion engines in general, are becoming increasingly stringent. To this end, various test procedures have been defined. Of course, vehicle emissions are regulated at the tailpipe, and we can either measure vehicle emissions as a whole (vehicle), or evaluate the engine alone. Most of the time, these measurements are carried out at ambient temperature, but with the advent of after-treatment systems, the notion of catalyst activation time has become fundamental. It is estimated that around 80% of CO and HC are emitted when the catalyst is not yet activated. To the procedures carried out at room temperature, a procedure with measurements at – 7 °C has been added.

Initially, the standards were aimed primarily at new vehicles, but the notion of durability was introduced, with checks carried out after a certain number...