Why?
First, it spoils environment. It's an environmental pollution. Then, cars are very expensive, most of people can't afford to pay such large money. If you say the car is very fast,it can help us arrive some places quickly,I 'll tell you you also can take a bus . The tickets of the bus are very cheap. Last, cars need petrol. There isn't much petrol in the earth, and petrol is expensive, too.
I don't think it is useful to have a car in a city.
Let's keep the air clean, don't buy cars.
Let's go to work by bus.