Final answer:
Nitrogen Dioxide (NO2) is the oxide produced in car engines when atmospheric nitrogen and oxygen react due to the high temperatures during combustion.
Step-by-step explanation:
The oxide produced by the sparking of air in car engines is Nitrogen Dioxide (NO2). In the high-temperature environment of a car engine, atmospheric nitrogen reacts with oxygen, forming various nitrogen oxides (NOx), among which nitrogen dioxide is a significant component. This gas is not only a by-product of the internal combustion but also a contributor to the formation of ground-level ozone, which poses various health risks and is part of the broader category of pollutants known as NOx. While metallic oxides are relevant in different contexts, they are not the primary product of air sparking in car engines.