ORLANDO, Fla. —Sixty-four million U.S. drivers would not be able to pay for an unexpected vehicle repair without going into debt, indicating that some drivers may underestimate the full cost of owning and operating a vehicle, according to a new AAA survey.

The average repair bill, according to AAA, can set a driver back up to $600, but costs can soar if a vehicle isn’t well maintained. And according to a separate AAA survey, one-third of U.S drivers skip or delay recommended services or repairs, which increases the likelihood of unexpected mechanical failures and roadside breakdowns. Last year, AAA responded to nearly 32 million stranded motorists.

“The average cost of owning and operating a vehicle is more than $8,500 a year, and AAA has found that millions of Americans are failing to set aside a car care fund to pay for the upkeep of their cars,” said John Nielsen, AAA’s managing director of automotive engineering and repair. “To avoid a surprise down the road, drivers should budget for monthly payments, insurance premiums, fuel costs and the inevitable expenses of routine maintenance and repair.”