Everyone from the budget director to the most penurious taxpayer knows that local governments here and elsewhere are under intense pressure to maintain public services and keep costs down. Is this an impossible dream?

Robert S. McNamara, recently retired president of the World Bank and former boss of both the Ford Motor Co. and the Pentagon, will head a task force to seek an answer to that question as it affects governmental units in the Washington area. Formation of the task force was announced yesterday by the Greater Washington Research Center, a respected think tank on regional issues.

The center's executive vice president, Atlee Shidler, said the 30-member group, will look at such questions as: What services must local governments provide? How can they improve their economy and efficiency in providing those services? What new revenues are available? What services can they drop or leave to others?

For six months, task force members will meet twice monthly to collect facts and opinions from experts. After draft reports are prepared, public comments will be solicited. A final report containing recommendations will be issued early in 1983.

Other officers of the task force are John J. Byrne, chairman of Geico; William Gorham, president of the national Urban Institute, and LaSalle Leffall, chairman of the surgery department of Howard University Hospital