How much is too much for a car payment?

Today's consumers deal with a world in which some costs go up far faster than their incomes. As interest rates rise, the cost of existing debt on credit cards and other variable-rate loans will go up too.

Before shopping for a new car, SUV or truck, it's becoming more important than ever to start out asking: What exactly can I afford? What's a reasonable monthly payment? What other costs do I need to consider? And, really, how long do I expect to hold onto that new vehicle?

"A lot of cars here today are 50 grand or more. Most people can't afford that," Ryan Fortenbacher, 35, said as he visited the North American International Auto Show in Detroit earlier this month. "What you used to be able to get for $20,000 is now $30,000."

Fortenbacher, a real estate agent from Columbus, Ohio, said he and partner Mark Fischer pay $260 a month for a Volkswagen Jetta and $360 a month for a Toyota 4Runner.

The Toyota is a three-year lease, he said, because it would have cost nearly $700 a month on a five-year car loan for the $38,000 SUV. The Jetta has a 72-month loan at zero percent.

"If you asked me 10 years ago, I would never have done that," he said of the six-year car loan.

One risk of a lengthy loan is you can owe far more than the car is worth if you want to unload it before you pay it off.

On average, consumers are paying $495 a month for new-car loans, based on data for third quarter 2016, according to credit-reporting service Experian. That's up from $447 in 2008. By contrast, the average interest rate on a new-car loan was 6.14 percent in 2008, compared with 4.69 percent in 2016.

"We've seen a pretty sizable increase in monthly payments in the last eight years," said Melinda Zabritski, senior director for automotive finance for Experian.

On average, consumers financed $24,060 for a new car in 2008, compared with $30,022 in third quarter 2016, according to Experian's data.

Some of the higher debt can be explained by higher sticker prices. Added technology drives up costs, too. The popularity of pickups and crossover utility vehicles also factors into bigger average payments.

In 2008, the No. 1 spot for new-car sales was small economy cars, Experian's Zabritski said. Now, the No. 1 spot is a more expensive, entry-level cross-over utility vehicle such as a Toyota RAV4, Honda CR-V or Ford Escape, she said, followed by the pickup truck, then the economy car.

The average loan on an entry-level CUV was $25,966 from January through November 2016 - roughly $5,128 more than for a small economy car. The average loan on a full-sized pickup: $39,039.

Zabritski noted that the average new-car loan rate for a small economy car was 7.39 percent last year through November, reflecting a price point that attracts more subprime borrowers, who face higher interest rates due to bad credit. The average payment: $363 a month.

Though many observers say the auto industry can keep selling at high levels or a slightly lower pace, some wonder if a roadblock is just ahead.

"We believe car affordability is holding new-car sales back," said Michelle Krebs, senior analyst for Autotrader.

U.S. consumers bought a record 17.55 million new cars and trucks in 2016 - up from 17.47 million in 2015. But those sales are not that far off the old record level of 17.35 million sales hit in 2000.

If you look at the growth of the adult population, Krebs said, it's theoretically possible another 3 million units could have been sold in recent years.

In 2000, the U.S. had 210 million people over age 18. By 2015, the country had 248 million people over 18, she said. So, essentially it took 38 million more people to reach something close to 2000 levels.

"Why aren't we selling 20.5 million new vehicles?" she asked. "Affordability. In our recent survey of consumers, we asked: 'Why do you think you may not own or lease a new vehicle in the future?' Fifty-seven percent said they couldn't afford it."

Many consumers stretch out loans or lease cars to keep a lower monthly payment. About 30 percent of new cars sold are leased, according to Experian.

About 30.7 percent of new-car loans are for 73 to 84 months, it says, with about 40.7 percent for 61 to 72 months.

Often, consumers don't bring much money to the table to buy a new car, financing 90 percent of their vehicles on average, said Paul Traub, senior business economist for the Federal Reserve Bank of Chicago's Detroit branch.