DENVER — On Thursday the Bell Policy Center, a research and advocacy organization based here that seeks to promote economic opportunity, added its voice to the rising tide of concerned politicians, safety workers, and activist groups opposing Ballot Initiative 300, Denver's so-called impound initiative, which would require police to seize the vehicles of any drivers failing to carry a valid license. Initiative 300 is an updated version of Initiative 100, which passed last year. According to Rich Jones, director of policy and research for the Bell Center, Initiative 300 is not only fiscally unsound but is racially motivated.