<prompt> Human: Hello,I wanted to ask you guys for advice that I can give my girlfriend who is looking to finance a car. Shes 19 with no credit, no one willing to co-sign and shes extremely desperate to get a car. I fear that shes willing to go with anyone who approves her for a car. Whats some advice that I should give her in this situation? I tried to tell her to take her time but since we were brought up differently, she thinks I dont understand her struggles.  <response>: Theres the 20-4-10 rule of car buyingfinancing. minimum 20 down payment. maximum 4 year loan 48 months maximum 10 of net monthly income towards net monthly transportation expenses payments, insurance, gas, etc.If she has to break one of these rules to get a car, she cant afford that car. 