In short, no.
It's not true. A committee formed by the California EPA was exploring ways to make cars more efficient, including ways to lower AC use in order to lower the resulting Carbon Dioxide emissions. They toyed with the idea of making car paints use more reflective materials. In addition to the finding that such materials would not be cost effective, the fact that jet black could NOT be able to be made more reflective caused them to DROP THE IDEA!!!
Do you really still believe these mass emails that are sent around?