Sometimes a new business owner has planned to start their own business for a while before they make the move. In this situation a lot of planning can take place.
A bank is more comfortable lending money to a person who has a job as opposed to a person who has just quit their job and is calling themselves self-employed. In this situation that person just looks like they are unemployed to a bank.
The strategy would be to get the new car you need before you quit your day job. Do you need a line of credit on your house again? You would get that before you quit.
I am not suggesting that you lie to a bank, but I would be very surprised if a bank manager asked you if you planned to quit your job when they are renewing your credit.