TACOMA, WAThe Tacoma Police department is adding four hybrid cars to its fleet of unmarked vehicles, to be outfitted with emergency lights and other equipment. The additional vehicles will be driven by detectives, according to The News Tribune.

The move is part of a citywide effort to reduce greenhouse gas emissions and help curb global warming. The city has 45 hybrid vehicles, used by Tacoma Public Utilities, the Tacoma Fire Department, and other agencies.

The police hybrids — a Chevrolet Malibu and three Toyota Priuses — cost more than the department had budgeted, but officials hope they'll save money in other ways, including improved fuel efficiency and lowered gas emissions, reported the Tribune.

Last year, the police department had planned to buy eight Chevrolet Impalas to replace eight unmarked Ford Taurus models that had reached the end of their 10-year life cycle. At the end of a vehicle's life cycle, money is pulled from the fund to buy a new rig. The old cars are sold at auctions. Some are donated to Goodwill, said Fred Chun, the city's Fleet Services manager.

Instead, the Fleet Services Department persuaded police officials to buy four Impalas and four hybrids, and help pay for the new hybrids. The cars furthered the Fleet Services Department's efforts to implement the city's Climate Action Plan. There are currently no plans to equip hybrids as fully marked patrol cars.