Should you finance a car or pay cash?

You have enough to buy the car outright. Should you?

The textbook version is a rate comparison: if the loan costs less than your money earns, finance. That is the right structure and it misses the thing that usually decides the answer at a dealership.

The dealer's offer is a choice, not a menu

This is the part to get straight before any arithmetic.

Manufacturer incentives generally come in two forms, and you usually have to pick one:

• A cash rebate — a reduction in the price
• Promotional financing — 0.9%, 1.9%, 2.9%, well below market

They are normally alternatives, not additive. Take the 0.9% and the $2,500 rebate disappears. Take the rebate and you finance at the standard rate, or pay cash.

That converts the question from "finance or pay cash" into a concrete comparison:

On a $35,000 car, a $2,500 rebate against 0.9% financing over 60 months is a genuine head-to-head calculation with a definite answer, and it is the calculation the finance or pay cash calculator is built around. Sometimes the promotional rate wins, often the rebate does, and the only way to know is to run both.

A related trap: a cash discount is frequently smaller than the rebate available with financing, because the manufacturer subsidizes the financing. Which means paying cash can cost you the incentive entirely. Ask explicitly what the price is with cash, with the rebate, and with promotional financing — three different numbers.

The rate comparison, done properly

Once the incentive question is settled, the comparison is the ordinary one:

Paying cash saves you the loan interest, guaranteed. That is a certain return equal to the loan rate.

Financing keeps your money invested. That is an uncertain return, taxed, at whatever the market delivers.

So the same logic applies as in paying off debt versus investing:

• Above about 8%, paying cash is hard to argue against.
• Below about 4% — which is exactly where promotional financing sits — financing usually wins over a reasonable horizon, because a guaranteed 1.9% return is a poor use of capital.
• In between, it is close, and the tiebreakers are liquidity and temperament.

Note the direction promotional financing pushes this: at 0.9%, keeping the cash is almost certainly correct, because virtually any use of the money beats 0.9%.

Three things that favour cash beyond the rate

No negative equity. Paying cash means you never owe more than the car is worth, which removes the gap-insurance question entirely.

Cheaper insurance options. A lender requires comprehensive and collision coverage. An owner with no loan can choose, which on an older car is a real saving.

No payment. Not an arithmetic point, but a real one. A fixed monthly obligation reduces flexibility for as long as it runs.

Three things that favour financing

Liquidity. $35,000 in a car is unreachable. $35,000 in an account is available for an emergency, a job loss or an opportunity. Draining savings to avoid a 3% loan and then borrowing at 24% three months later is a common and expensive sequence.

The promotional rate itself, where available, is usually below inflation.

Building credit, which is a minor benefit but a real one for someone with a thin file.

The middle option people forget

You do not have to choose the extremes. A large down payment with a short loan captures most of both: you keep a cash buffer, you take a small loan, you are never underwater, and the interest is modest because both the balance and the term are small.

If the promotional rate requires financing a minimum amount or a minimum term to qualify, finance exactly that and no more.

What to ask

1. What is the price with cash, with the rebate, and with promotional financing? Three numbers. Ask for all three in writing.
2. Are the rebate and the promotional rate combinable? Usually not — confirm.
3. What would paying cash leave me with? If the answer is no emergency fund, that settles it.
4. Is there a prepayment penalty? Without one, financing and then paying early keeps the option open.
5. What does the loan require me to insure? Comprehensive and collision are usually mandatory and cost real money.

The rate comparison is the easy half. The incentive question is the half that actually moves the number, and it is the one most buyers never ask about.

Sources: the rate comparison rests on the same arithmetic as paying off debt versus investing, whose tax figures are read from the constants the calculators use. Rebate-versus-promotional-rate terms are set by each manufacturer and are not a published national rule — the point here is to ask for all three prices in writing, since the answer is specific to the offer in front of you.