Among non-metal substrate coatings, plastic substrates have certainly asserted themselves as a key market, especially in the automotive industry. The substrates within exterior automotive industries are being diversified and commercialized at a rapid pace. Mainly attributed to the emergence of electric vehicles, environmental regulations, and functional requirements, there is huge scope and many opportunities for advancements and groundbreaking technologies. The above factors have led to the dawn of new and improved coating materials within the revolutionizing new substrate market. At the same time, new product innovations within ultraviolet (UV)-curable technologies, powder coating, nanotechnologies, and several other platforms have brought the possibility of novel coating systems into the picture. This review outlines the inherent challenges, the progress made thus far, and the future opportunities of two significant exterior plastic substrates: thermoplastic polyolefin (TPO) and polycarbonate (PC). While the former serves as the historical choice for plastic bumpers across the globe, the latter has captured the most research attention in recent times as a lightweight option against glass coatings. A meticulous overview of the existing literature was conducted to summarize the recent approaches with a few critical analyses. To surpass the challenges to the equivalent performances, a few of the most promising research studies were also examined, including the sustainability aspect.