5.11 understand that, in car engines, the temperature reached is high enough to allow nitrogen and oxygen from air to react, forming nitrogen oxides

In car engines, crude oil fractions (such as diesel or petrol) are burnt (as fuels). When fossil fuels are burnt, nitrogen oxide and sulfur dioxide are always released, always. When the temperature is high enough, the nitrogen and oxygen in the air react (this creates nitrous oxides, such as nitrogen monoxide and nitrogen dioxide).

NOTE: remember nitrogen oxide and sulfur dioxide are always produced when fossil fuels are burnt.