Here is what I don't understand. Why are used/new car loans at such low interest rates while personal loans are at 8% or higher? Is this because they put a lien on the car if you get a "car loan".
Yup. That is exactly why secured loans have much cheaper interest rates.
I don't want a lien on my car because that requires me to get a lot of insurance coverage such as collision/comprehensive which I don't want to pay for because it's expensive.
Well, you are just going to have to make a choice then aren't you.
Break out the spreadsheet, and computer the costs.
A) Sell $15,000 in bonds
B) Sell $15,000 in stocks
C) Get a personal loan at 8% interest + finance charges
D) Get a auto loan @4.5% interest (+ costs of comprehensive coverage - normal coverage) for the life of the loan.
Do the math & figure out which is the better deal & do it.