PARKING spaces on the Upper West Side are precious resources, to be hoarded like coal in wartime. The familiar street-cleaning shuffle requires paramilitary levels of vigilance and guile. So it is no surprise that the city is eyeing the neighborhood as a place to test a new program that would raise and lower the price of parking to match demand.

The system, known as performance-based pricing, was pioneered by Donald Shoup, a professor of urban planning at University of California, Los Angeles. Under the system, which is in use in Pasadena, Calif. and part of Washington, D.C., the price of parking fluctuates over the course of the day.

In peak periods, like the early evening, prices are kept high enough to dissuade some drivers from parking, with the goal of having two spots per block unoccupied at any time. Advocates of the system say it eases congestion and lowers emissions by sparing drivers the usual "cruise" in search of parking.

Over the last year, officials of the Columbus Avenue Business Improvement District have told the city they are willing to try out the new system, in return for street improvements like bike racks, benches, curb extensions and bike lanes. The city never formally agreed to such an arrangement, but Barbara Adler, executive director of the business district, said she learned a few weeks ago that performance-based pricing might be in the works for the avenue.