It used to be if you were paying cash for a vehicle, you could get a better deal from the dealer because they could get their money quickly and did not have to wait on the banks. Now dealers are getting a cut from the banks and prefer you finance through them. They usually charge much higher interest in order to receive a higher cut.
The next time you need a new ride, pay cash. As cash is always cheaper than financing in the end. If you must finance the. Do not go through the dealer. Instead, you should always try your local credit union first. You must be a member of a credit union but membership is usually quite easy to get. Rates can be as low as 1% for a car loan whereas a dealer will charge over 10%. For a 5 year loan of 20,000, that's a difference of about $5000 in total interest.
The order of precedence for purchasing a vehicle should be
2. Local credit union
3. National credit union
4. Small local bank
5. Big national bank
(If you get along with your parents then maybe borrowing from them can be number 2)
Assume you buy a $20,000 vehicle fully financed. At 10% interest over 5 years your monthly payment will be $424.94 for a total of $25,440 after 60 months. At 1% interest, your monthly payment will be $341.87 for a total of $20,512.2 after 60 months. Therefore your total PT savings are $4,928 in interest saved.