Cash vs Finance a Car
The rate test that settles the argument.
Finance: loan cost (interest paid):
Cash: what your money could earn invested:
Better choice:
What the comparison actually tests
Paying cash costs you the full price today. Financing keeps your cash invested but adds loan interest. The calculator compares the interest you would pay on the loan against what your cash could earn if you invested it instead.
Worked example
A $30,000 car with $30,000 cash available, a 6% loan over 60 months, and cash earning 5%: financing costs about $4,800 of interest while the invested cash earns about $4,200, so the loan is roughly $600 more expensive than cash - but leaves you liquid the whole time.
When cash wins
- Loan APR is higher than what your cash can realistically earn.
- You value the guaranteed saving and hate debt.
When financing can win
- You can get a low promotional rate (2-4%) and your cash would earn more in the market.
- You need the emergency buffer and would otherwise drain savings to buy the car.
One trap: financing to invest only works if you actually invest the cash. If the money would sit in a checking account, just pay cash.
Frequently asked questions
What return should I assume for invested cash?
Use a conservative after-tax number - 4-5% for a balanced portfolio - not the 10% stocks sometimes average in a single great year.
A practical middle path
Many buyers put down a large down payment and finance a small balance. That keeps an emergency cushion in the bank, limits the interest paid, and avoids the all-or-nothing choice. Try it in the calculator: a $15,000 down payment on a $30,000 car at 6% over 48 months keeps the payment modest while leaving real cash on hand.