The researchers studied how much greenhouse gases cars in Izmir city emit. They wanted to see how these emissions contribute to global warming. To do this, they counted how many cars were in Izmir and figured out how much carbon dioxide each type of fuel the cars used produced. The total CO2 emissions from 821,391 cars in Izmir was calculated at 1,857,845 tons per year. This helps in understanding the impact of cars on the environment and how we can work to reduce it.