The number of cars is growing along with the economic growth of a country

In twenty years there will be fewer cars in use than there are today.

At first I should say that I totally disagree with the statement above.
To begin with, many countries in the world are still developing. The number of cars is growing along with their economic growth. For example, many families are too poor to afford a car in the past in China. The statistics show that several family possess only one car on average. Nowadays as the improving of people's quality of life, the number of families who can afford a car is increasing. This lead to the continuous increase in the car demand and consume. There is no sign show that this trend will reverse.

For those developed countries such as US, the population density is relatively low and each person in those countries possess higher per capita hold of resources. Many car-related problems existing in the developing countries such as congestion and high oil price are not a problem for them. For those people, car bring them a convenient life and yet, at the same time no much extra cost compared with public transportation. Who will change their mind and turn to take buses under this circumstance?

Last but not least, we can use bike or others as a substitute when going a short distance. But if comes to 10 miles or even longer, a car is necessary. There is still no good car substitute now.

Based on above reasons, I firmly believe that the car number will not drop in 20 years.

At first I should say that I totally disagree with the statement above.
To begin with, many countries in the world [...] are too poor to afford a car in the past in China.

My suggestion, I think you must give paraphrase, give the word statement about this topic, and then give your opinion
The modern area already develops technology in the world. While as the prediction that the majority of people have the individual car to use in each people, this situation renders the other choice to occurred in t.he future. I believe that the different condition does not prediction by fast

Dear Cathy, you must write an introduction before explaining your idea about the case. In academic writing, the readers do not have access to read the task. So, you have to make sure that you have enough clues about the topic so that your writing is not confusing. Here is an example of introduction based on your idea.

In twenty years there will be fewer cars in use than there are today.

The number of cars in the world is predicted to experienced a drop 2 decades later. In my opinion, this prediction is not true because there are no sign of reduction in the number of vehicles both in developing and developed countries.

That's the simple instance of introduction. I do not know the task, is it require a solution or just discuss both view. So, you can make more detailed introduction according to the task.

hi cathy,

i think you should consider about paragraphing.
in academic writing, you should make your writing more well-structured, so for introduction you should mention about the content or topic, after that try to re-state the statement. Finally, you should give your opinion and statement and strong position.

in your body paragraph,

1. giving supporting detail by adding explanation or reason
2. giving a reliable example that more specific
3. giving a conclusion to emphasize your statement.

for example,

To begin with, many countries in the world are still developing. The number of cars is growing along with their economic growth. For example, many families are too poor to afford a car in the past in China. The statistics show that several family possess only one car on average. (add sequence) in addition/furthermore nowadays as the improving of people's quality of life, the number of families who can afford a car is increasing. This lead to the continuous increase in the car demand and consume. There is no sign show that this trend will reverse.