Cars are larger, you can take your whole family together in one vehicle. If, however, only one person is travelling, it is more efficient to use a motorcycle.
Cars are better in bad weather. If there is rain or wind, riding a motorcycle can be uncomfortable and more dangerous than a car. In a car in wet weather you can be warm and dry.
In very hot weather, too, a car fitted with air-conditioning will be more comfortable. A sensible motorcyclist will always wear protective clothing which can be very warm.
When traffic is encountered a motorcycle is much better than a car. Cars get stuck in traffic jams which can hold you up for hours. A motorcycle, on the other hand, can squeeze down the channels between cars and beat the jams.
A motorcycle is also more efficient than a car. The engines are usually smaller and so more miles can be covered on the same amount of fuel.
The main drawback for a motorcycle is the safety aspect. Motorcycle riders are much more vulnerable to accident and there is far less protection for them. Modern cars are designed to protect drivers and passengers from harm, but a motorcyclist can only rely on clothing and a helmet.