The Trade and Cooperation Agreement imposes different forms of non-tariff barriers on UK-EU trade relation. In my thesis, I evaluate the trade and welfare effects of NTBs by analysing the different channels through which they affect one of the key industries of the UK, the automotive sector. Before delineating the most important features of the internationally fragmented European automotive supply chain, I also present the theoretical background of intra-industry trade, given its significance in the automotive. The two main types of IIT, vertical-and horizontal IIT are also described and related to the UK's automotive sector. Based on the relevant literature and my own calculations, it is expected that NTBs will cause disruptions in just-in-time supply chains, while uncertainty and rule of origin regulations may force some of the foreign car manufacturers out of the UK. Leaving the Single Market means more autonomy in trade negotiations with non-EU countries for the UK, however, the related advantages are not so obvious in the short-run. Finally, I conclude that even though the USA is a major export market and a very important trade partner for the UK, it cannot be expected that a deeper integration that could recover the Brexit's welfare losses will be reached between the two Parties, given the just-in-time nature of the international supply chains in the industry, where distance plays a crucial role.