The Environmental Protection Agency is proposing that automakers test several thousand of their customers' cars each year to determine whether their fleets meet federal pollution requirements.

The new tests would be conducted one year and again four years after they are sold to better determine pollution control performance under actual driving conditions.The tests would be part of a broader overhaul of the EPA's certification process for cars aimed at reducing paperwork and costs to manufacturers.

EPA Administrator Carol Browner said the proposed streamlining would save auto manufacturers $55 million a year and thousands of hours of reduced paperwork.