HOUSTON (AP) — Houston is adding 50 electric cars to the municipal vehicle fleet for city employees across numerous departments to share.

Mayor Annise Parker says a new partnership with the car-sharing network Zipcar Inc. is the reason for the fleet additions. A city statement says the program is the first of its kind to utilize electric vehicles.

The City of Houston has the third largest municipal hybrid fleet in the nation, with about half of the city's general-purpose, light-duty fleet having been replaced with hybrid vehicles.

The city agreed to a three-year contract with Zipcar after competitive bidding.