A State Department of Community and Economic Development study says four Central Bucks municipalities could save more than $375,000 in the first year by merging their police departments. They are Doylestown and New Britain Boroughs and Doylestown and Warwick Townships.  Warwick would save the most at $246,978, while Doylestown Borough would save the least at $10,989, but benefit more in other ways by moving out of a station that is too small for today’s needs.  The study says they would save money by reducing the staff a little bit and making investigations more efficient.  Local officials will share the study with their residents over the next two months.