Liz Weston: The never-ending car payment

One-third of millennial car buyers chose a lease last year, which helped push auto lease volume to a record of 4.3 million and 31 percent of all new auto purchases, according to market research by Edmunds.com.

"There is a greater percentage of people who view car ownership as a monthly payment like their cell phone or cable or Wi-Fi," says Jessica Caldwell, executive director of strategic analytics at Edmunds.com.

Many people would rather have constant payments and continually drive newer cars than be surprised by repair costs — especially in an era when 46 percent of households don't have $400 in savings to cover an emergency, according to the Federal Reserve .

Auto loans that stretch six years or more mean buyers often face big repair bills while they're still making payments.

Too many of these buyers wind up trading in their cars before they've paid off their loans, rolling their negative equity into their next vehicle at even higher interest rates.

If your payment pushes your "must-have" expenses — such as shelter, transportation, food, utilities, insurance and other minimum loan payments — to over 50 percent of your after-tax income, you probably can't afford it.

Car repairs are typically covered under warranty when you lease, but you may face extra charges at the end for excessive mileage, bald tires or wear and tear, especially if you are not leasing another vehicle of the same make .