$B$ is a $17-$year$-$old young lady. She lives with her parents, but works as a petrol attendant at the local petrol station. She controls her own income and pays rent to her parents. She buys a car on hire purchase from a car dealer. While signing the papers for the car, she tells the car dealer that she is $21$ years old. She pays one instalment and thereafter fails to make payments. The car dealer wants to sue her for the full amount but when he discovers B$\text{'}$s true age, he approaches you for advice.

Do you think the car dealer would be successful if he were to sue B for the full amount? Support your view.