About Car Finance Garage

Car Finance Garage was created by John Brandenburg while he was in the process of buying a new car and trying to determine the best way to fund the purchase. He built several spreadsheets to answer that question, then decided to turn the spreadsheet models into an app. That app became this website: Car Finance Garage. The browser-based calculator answers a specific car-buying question: which funding path actually costs the least after interest, taxes, rebates, and missed investment growth are considered together?

What it compares

The app compares dealer or bank financing, a 401(k) loan, taxable investment liquidation, and hybrid strategies. Users can save multiple vehicles, adjust assumptions such as market return and capital gains rate, and compare purchase economics with five-year ownership costs.

Privacy by design

The calculator runs locally in the browser. Saved cars and settings stay in browser local storage on the user's device unless the user exports a JSON backup and shares it elsewhere. There is no account system and no application backend for garage data.

Not advice

The output is educational and depends on user-entered assumptions. It is meant to support a better conversation with a lender, accountant, or financial planner, not replace professional advice. You can also find John's related work on GitHub.