One of the most popular mechanical devices is a car. A car is a road vehicle used to carry passengers. You can easily move from one place to another by car. It is very comfortable. Cars are faster than walking or riding a bike if you are going a long way.  There are a lot of different types of cars.  A car can often go where public transport can not. But cars have also disadvantages. They pollute our atmosphere. Emissions from cars are very dangerous.