The first thing you should be clear about is that financing options for craigslist used cars vary due to numerous factors. Sometimes, it has to do with the tie-ups the automobile manufacturing company has with a particular bank or credit card company. You could, for instance, get a lower interest rate if you pay for your car with a Visa credit card than American Express. The same way goes if you choose Bank A over Bank B.
If you want to increase your savings when purchasing a car, you should then speak with your bank manager and see if your bank has any such tie-ins with other automobile manufacturers.
Financing options also vary depending on the type of car that you intend to purchase. Some companies offer five-year financing for their most expensive models but only offer three-year financing for lower-end models.
Lastly, the loan amount that you can get will always depend on your credit score.