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How Car Loans Work
APR, term length, and total cost
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A car loan lets you buy a vehicle now by borrowing money and paying it back over time. The amount you borrow is called the principal, and the lender charges interest for letting you use the money. Understanding how loans work helps you compare offers, avoid overpaying, and choose a payment that fits your budget. Even a small difference in APR or term length can change the total cost by hundreds or thousands of dollars.
Each monthly payment usually includes both principal and interest. At the start of the loan, a larger share of the payment goes toward interest because the balance is still high. A longer loan term can lower the monthly payment, but it usually increases the total interest paid. Comparing loan amount, APR, term length, and total cost gives a clearer picture than looking at the monthly payment alone.
Key Facts
- Principal is the original amount borrowed, such as a $20,000 car loan.
- APR means annual percentage rate, which is the yearly cost of borrowing shown as a percent.
- Monthly interest rate = APR / 12, so 7% APR gives r = 0.07 / 12 = 0.005833.
- Monthly payment formula: M = Lr(1 + r)^n / ((1 + r)^n - 1), where L is loan amount, r is monthly rate, and n is number of payments.
- For a 617.54 and total interest is about $2,231.44.
- For a 396.02 and total interest is about $3,761.20.
Vocabulary
- Principal
- The principal is the amount of money borrowed before interest is added.
- APR
- APR, or annual percentage rate, is the yearly cost of borrowing money expressed as a percent.
- Loan Term
- The loan term is the length of time you agree to take to repay the loan.
- Monthly Payment
- The monthly payment is the fixed amount paid each month to repay the loan and interest.
- Total Interest
- Total interest is the extra money paid to the lender beyond the amount originally borrowed.
Common Mistakes to Avoid
- Looking only at the monthly payment is a mistake because a lower payment can come from a longer term that costs more in total interest.
- Confusing APR with the monthly interest rate is a mistake because APR is yearly and must be divided by 12 for monthly loan calculations.
- Ignoring the loan term is a mistake because stretching payments over more months usually increases the total interest paid.
- Thinking the car price is the same as the loan amount is a mistake because down payments, taxes, fees, and trade-ins can change how much is actually borrowed.
Practice Questions
- 1 A student borrows 617.54, find the total amount paid and the total interest paid.
- 2 A student borrows 396.02, find the total amount paid and compare the total interest to the 36-month loan.
- 3 Two loans have the same principal and APR, but one lasts 36 months and the other lasts 60 months. Explain why the 60-month loan has a lower monthly payment but usually costs more overall.