Research from the Lawrence Berkeley National Laboratory (LBL) indicates that they definitely are. In partnership with the EPA, LBL has studied the ability of urban materials to reflect light and absorb heat. The above graphic is of Washington, D.C. and the hot colors indicate the heated locations. Some of this research was co-authored by the current Secretary of Energy Steven Chu before taking his current post.
In general the phenomenon is referred to as the "urban heat island." Interestingly, as asphalt ages and goes from black to gray, the ability of pavement to heat up decreases, as seen in the graph below. That's just about the time when a new application of coal tar sealants is applied to return it to a heat absorbing, deep black color.
So how significant is this heating? Dr. Chu states that appropriate cooling of urban impervious surfaces, roofs and pavement, would be the equivalent of removing the carbon emissions of all of the cars in the world for 11 years! In Austin, Texas just reducing the sealant color from "new asphalt black" to aged gray, there is a measurable reduction in energy consumption by the 500,000 households there.
The cost of hotter cities is not just in the electric bill either. It also increases the production of lung-damaging ozone, which in turn can cost not only health care and productivity costs, but also compliance costs and jobs.
As you can see below the pavement percentage of a city is different across the US, but it is about double the surface area of rooftops. With the frequency of sealant application much more often than roof replacement, doesn't it make sense to know which non-toxic products reduce our urban pavement furnaces?