Car Loan True Cost Calculator: Dealer vs Credit Union vs Cash
Example: Vehicle price (before taxes and fees): 35000 $ · Down payment: 5000 $ · Dealer-offered APR: 9.9 % · Credit union pre-approval APR: 6.49 % · Loan term: 60 months
| You save vs dealer by using credit union | $2,946 |
| Dealer financing monthly payment | $636 |
| Credit union monthly payment | $587 |
| Total cost with dealer financing | $43,156 |
| Total cost with credit union | $40,211 |
| You save vs dealer by paying cash | $8,156 |
| Total interest with dealer financing | $8,156 |
Worked example
A $35,000 car with a $5,000 down payment leaves $30,000 to finance. At the dealer's 9.9% APR over 60 months: $638/month, $8,280 in interest, $43,280 total. With a credit union pre-approval at 6.49%: $585/month, $5,100 in interest, $40,100 total. The credit union saves $3,180 over the loan — simply by walking in with a competing offer. A cash buyer pays exactly $35,000, saving $8,280 versus the dealer. The lesson: pre-approved financing is leverage, not a minor convenience.
Frequently asked questions
Can I negotiate the APR with a dealer?
Yes — dealers frequently mark up the rate they offer above the buy rate (the rate the lender actually requires). The markup is dealer profit and is negotiable. Walking in with a credit union pre-approval forces the dealer to compete or lose the financing business. In some cases, the dealer's captive lender offers promotional rates (0% APR on select models) that beat credit unions — compare both.
Does paying cash give me negotiating power on the price?
Sometimes, but the effect is smaller than many buyers expect. Dealers make less profit on cash sales (they earn nothing from financing), so some dealers prefer financed buyers. A better negotiating sequence is to negotiate the out-the-door vehicle price first, agree on that number, and then discuss financing — never let the conversation be about monthly payment alone.
What is a credit union pre-approval?
Before you visit a dealership, apply for an auto loan at your credit union or bank and get a pre-approval letter stating the maximum loan amount, APR, and term they will offer. This functions as cash from the dealer's perspective and gives you a firm benchmark to compare against dealer financing. Pre-approvals typically do not expire for 30–45 days.
Are there costs this calculator does not include?
Yes. Taxes, title and registration fees, dealer documentation fees, and add-ons (extended warranties, GAP insurance, paint protection) can add $1,000–$5,000 to the actual transaction. This calculator isolates the financing cost comparison only. Always negotiate the out-the-door price before agreeing to any terms.