Engine models are simplified representations of real-world engines used to analyze and predict their performance. These models can vary in complexity, from basic mathematical equations to detailed simulations that account for various factors like fuel type, temperature, and pressure. Engine models are essential in fields such as automotive engineering and aerospace, where they help engineers design more efficient engines. By using these models, engineers can test different configurations and optimize performance without the need for costly physical prototypes, ultimately leading to better fuel efficiency and reduced emissions in vehicles and aircraft.