Answer:
fad product.
Explanation:
Fad -
It is the product , which has very less or limited utility , but is responsible for a very immediate increase in the sale and publicity , but it is immediately followed by reduction in the price and publicity , is known as a fad product .
Hence , as given in the question , the sale of the small toy cars increases rapidly and gained extreme popularity but within few months , the demand of the car drop down .
