Warburg Pincus, a private equity firm, led a Series C round in Ambilight, a manufacturer of electrochromic technology-based auto rearview mirrors, ski goggles, and other products. Additional investors include BYD, NIO Capital and Cygnus Equity. Financial terms were not disclosed. The new financing will be used for the R&D of new electrochromic products, expansion of production capacity, and commercial promotion globally.