NEW YORK ( MainStreet) — A median-income household can only afford the average-priced new car in one of the 25 largest U.S. metro areas, according to a new Interest.com report.

All of those metro areas except for Washington, D.C. fell short of the $32,086 that it takes to buy the average new car. In many cases, the cities fell well short of the average price of a new car. Interest.com found that Tampa residents can only afford to spend $14,209 on a car. Sixteen cities fell short by $10,000 or more.

Washington, D.C. leads the list for a second straight year, followed by San Francisco and Boston. Two Florida cities (Tampa and Miami) bring up the rear and are the only two cities where car affordability declined over the past year. San Antonio experienced the biggest jump in affordability over the past year at 7%, followed by Phoenix at 6% and San Francisco and Atlanta, both at 5%.

Interest.com recommends that median-income households spend no more than the following amounts on vehicle payments, which include interest. For comparative purposes, the average price of a new car or light truck in 2013 was $32,086, according to Kelley Blue Book. That equates to a monthly payment of approximately $633. Residents in Washington, D.C. can afford to spend $32,531 on a new car or pay a maximum of $641 each month while people in San Francisco can buy a car for $28,009 and spend $563 each month.

Residents in Miami and Tampa were at the bottom of the list of 25 largest U.S. metro areas and consumers there can only afford to spend $299 and $280 respectively each month. More information is available here.

"Too many families are spending way too much on new cars and trucks," said Mike Sante, managing editor of Interest.com. "Just because you can manage the monthly payment doesn't mean you should let a $30,000 or $40,000 ride gobble up such a huge share of your paycheck. You can get a great car for much less and use the savings to invest in yourself. Here's where the money for your retirement or kids' college can come from."

When calculating how much a household can afford to spend on a car or light truck, Interest.com considered three key factors that are commonly referred to as the "20/4/10" rule: a down payment of at least 20%, financing lasting no longer than four years and principal, interest and insurance not exceeding 10% of a household's gross income. The calculator is available here.

Many consumers walk into a dealership without knowing how much they can afford to spend each month, he said.

"You wind up going to the car dealer who determines a lot of that thinking for you and they are good at grabbing every bit of discretionary income you have," Sante said. "You need to have a really firm price point in mind and stick with it."