How long should a car loan be? 36 to 84 months compared

Car loans used to be three or four years. Today, 72- and even 84-month loans are common, largely because cars have become more expensive and a longer term makes the monthly payment look manageable. But a lower payment isn't the same as a cheaper car. Here's what term length really changes.

The same car, five different terms

Take a $30,000 loan at 7%. Here's how the monthly payment and total interest change with the term:

• 36 months: about $926 a month, $3,347 in total interest.
• 48 months: about $718 a month, $4,483 in interest.
• 60 months: about $594 a month, $5,642 in interest.
• 72 months: about $511 a month, $6,826 in interest.
• 84 months: about $453 a month, $8,034 in interest.

Going from 60 to 84 months lowers the payment by about $141 but adds almost $2,400 in interest. And that assumes the same rate. In reality lenders usually charge more for longer loans. At 8.5% over 84 months, the interest on the same loan comes to about $9,908.

The bigger risk: negative equity

Cars lose value fastest in the first few years. With a long loan, the balance also falls slowly in the early years, because most of each payment goes to interest. The combination often means you owe more than the car is worth for a long stretch. That's called negative equity, or being "upside down".

Negative equity becomes a problem when something changes. If the car is totaled, insurance pays what it's worth, not what you owe, and you're responsible for the gap unless you have GAP coverage. If you want to trade it in, the shortfall usually gets rolled into your next loan, so you start that loan already underwater. Repeating that cycle is one of the most common ways people end up with steadily larger car debts.

A common guideline

A widely quoted rule of thumb is 20/4/10: put at least 20% down, finance for no more than four years, and keep total car costs (payment, insurance, and fuel) under 10% of gross income. Few people meet all three today, but it's a useful benchmark. Many planners suggest 60 months as a reasonable upper limit.

When a longer loan can make sense

A longer term isn't always a mistake. If a lender offers a very low promotional rate, the extra interest may be small. If you need a reliable car and the lower payment is what keeps your budget safe, the flexibility has value, especially if you plan to pay extra when you can. The key is to choose it knowingly, looking at total interest and how long you'll be upside down, not just the monthly payment.

Negotiate the price, not the payment

Dealers often ask what monthly payment you're looking for. Answering can make it easy to agree to a higher price or a longer term that hits the number. It's usually better to negotiate the out-the-door price of the car first, then discuss financing. Getting pre-approved by a bank or credit union before you shop gives you a rate to compare against the dealer's offer.

Compare terms yourself

The auto loan calculator shows the payment and total interest for every common term side by side, and includes sales tax, fees, and trade-ins, including negative equity from your current car.