They started with four cars parked near Monument Square and the ferry terminal. Here's a screenshot of their website in 2009:
As of this fall, they've doubled the local fleet to 8 cars and expanded into South Portland with a car parked at the Southern Maine Community College campus. Here's their new coverage map:
A lot of UhaulCarShare's success here comes from a helpful new reform of parking rules in the city's zoning requirements. For the last few years now, city planners have allowed a reduction in developers' expensive parking-construction mandates if the developers agree to sponsor a carsharing vehicle on-site.
Several new apartment buildings have taken advantage of this incentive, most recently Avesta Housing's 409 Cumberland Avenue apartment block, which built only 18 basement parking spaces for its 57 new apartment units and sponsored a new UhaulCarShare vehicle to be parked on-site. This arrangement benefits everyone: reduced construction costs for the developers, reduced housing costs and more mobility options for residents, and a more convenient carsharing network for neighbors.