Compare dealer financing, a 401(k) loan, liquidated investments, or a hybrid plan to see which car-buying option actually costs you the least.
The monthly payment doesn't tell the full story. Dealer loan interest, the opportunity cost of pulling money from a retirement account, and the capital gains taxes triggered by selling investments all affect your real out-of-pocket cost in ways that only show up when you model them side by side. This calculator does that math for you.
Everything runs in your browser. No account required. Your saved cars and settings are stored in browser local storage — private, on your device only.
A normal car payment calculator answers one narrow question: what will the monthly payment be? Car Finance Garage answers a broader question: which funding path leaves you with the lowest modeled cost after interest, taxes, rebates, and missed investment growth are counted together. That matters when the cash for a car could come from taxable investments, a retirement-plan loan, a dealer loan, or a combination of sources.
The tool is designed for buyers comparing real tradeoffs, not only checking affordability. You can save multiple vehicles, adjust market-return and tax assumptions, compare scenarios, and include five-year ownership costs such as fuel, electricity, insurance, maintenance, registration, property tax, and tires.
Start by adding the vehicle price, taxes, down payment, and any manufacturer rebate. Then add the loan terms you were quoted, your expected market return, and the investment cost basis if you are considering selling taxable holdings. Add ownership-cost estimates when comparing different vehicles, because a car with a lower price can still cost more to own.
The result is an educational model, not advice. It gives you a structured way to see the assumptions that matter most before you talk with a dealer, lender, accountant, plan administrator, or financial planner.
Traditional auto loan
Finance through a dealer, bank, or credit union at a fixed rate over 36–84 months. Your investments stay untouched, but you pay interest to a third party. Often includes manufacturer rebates that can change the math significantly.
Borrow from your retirement plan
Borrow up to 50% of your vested balance (max $50,000) and repay yourself with interest. No credit check, no lender. The cost is the investment growth you forgo while the money is out of the market.
Sell from a taxable brokerage
Pay cash by selling holdings in a taxable account. No loan interest — but capital gains taxes on any appreciation, and that capital is no longer compounding.
Partial liquidation + loan
Finance long enough to capture a dealer rebate, then pay off the balance with a 401(k) loan or cash. Balances interest cost, tax exposure, and opportunity cost.
Read the full financing guide for a detailed explanation of each method, or see the methodology for the exact formulas used.