If you want to borrow a large sum of money from a lender, she is going to want to know what it is for. Buying a car is a big investment, one which could take some time to pay off, so it is reasonable that your vehicle loan application should come with a lengthy questionnaire, even if your parents are the one you are applying for.
The lender wants to know if you are buying a used or a new car. There is the potential for either one of these to be a good or bad investment. For instance, certain makes are notorious for particular problems that are costly to repair, or the model has been recalled numerous times. You might have done your research into the best make and model to buy, but the lender wants those details too if you have them. Pre-arranged financing is available just in case you have not chosen a car yet but wish to set a budget. Arranging a loan ahead of time also prevents consumers from signing a contract at the dealership without comparing interest rates first.
Perhaps you already have a car financing loan, but it is not satisfactory. Interest rates have come down significantly since you signed your contract and now you see that you could be saving hundreds of dollars each year. Although it is not wise to rush into anything, refinancing is a good idea when you feel like you are being ripped off. Just read all of the details of your existing contract and those of another, potentially better one. Look for hidden costs and limits to the deal which could make refinancing more expensive in the long run.