From my understanding, the FD is not broken. Loan is just that - a loan with the FD used as a security towards the loan. You need to repay the balance of interest (lending rate - FD rate) on the loan along with the principal. Generally you can repay chunk of the principal in bulk without any restriction and you can foreclose with no penalty.
Note that in a car loan, you pay the entire interest on the amount borrowed across the full term. So you effective rate of interest would be slightly higher than the interest rate mentioned. i.e. though you are repaying a part of principal + interest every month and even in the last part of the loan, the interest is still computed on entire amount since it is spread across the term.
That is why it makes sense to save on interest by borrowing from FD account, since you can repay the principal in bulk at any time and close the loan at your convenience.
Further in a car loan you have a hypothecation on the vehicle, which is in favour of the financier, which must be removed after repaying the loan in full (you need to get the NOC from financier and take it to the RTO for hypothecation cancellation endorsement in your RC). So in effect, the car belongs to the financier while the hypothecation exists - you are simply the "hire-purchaser".