Updated

Police working to keep the city safer will be trying to keep it greener too — by testing an electric, ultra-quiet scooter.

Four plug-in Vectrix scooters will be road tested starting early next month as the New York Police Department tries to become more environmentally friendly and reduce gasoline use in its massive motor fleet.

The nation's largest police department already uses a handful of hybrid cars and so-called flex-fuel vehicles, which can run on both gasoline and ethanol.

"Police effectiveness comes first, but where we can combine environmentally friendly vehicles without compromising the mission, we do," Police Commissioner Raymond Kelly said.

The sleek, two-wheel Vectrix scooters are the first all-electric vehicles to be government-certified to travel on any highway, street or road, said Andrew MacGowen, president of the Rhode Island-based company.

The NYPD says officers use the current fleet of regular-fuel scooters to patrol city parks, police street demonstrations or direct traffic.

The Vectrix has a top speed of more than 60 mph and is recharged by plugging it in a standard outlet for two hours. Its higher purchase price compared to other scooters would be quickly offset by the fuel savings, the department said.

Detective Derek Siconolfi, who will train riders, suggested the quiet engines also offer a side benefit: the element of surprise.

"You could easily sneak up on somebody if they don't expect it," he said.