Over recent years, international trade flows of automotive products have experienced rising trends. Thus, the need to gain a better understanding of trade theories that could explain such trade flows. Until recently, the theoretical and empirical distinction of intra-industry trade (IIT) into patterns of horizontally differentiated (by variety) intra-industry trade (HIIT) and vertically differentiated (by quality) intra-industry trade (VIIT) has become crucial because each IIT pattern may potentially be influenced in different manners by country and industry factors (Greenaway, Hine&Milner, 1995). The objective of this thesis is twofold. Firstly, to measure the empirical significance of IIT in the automobile industry between South Africa and its bilateral trading partners and to decompose total IIT (TIIT) into VIIT and HIIT patterns. Secondly, to develop empirical models to investigate potential country- and industry-specific determinants of IIT patterns in the South African automobile industry. The empirical strategy adopted in this thesis is a gravity model spanning the period 2000 to 2007. The automobile industry is a principal industrial sector in the South African economy contributing notably to trade, investment, employment and national output. The structure and conduct of the industry is aligned with several elements of IIT theories and thus represents an important and fascinating case of IIT patterns to investigate. Therefore, the findings of this thesis will be valuable to trade policy analysts and manufacturers in the local and global automotive industries. According to the objectives, the significance of IIT is estimated using the trade overlap index and the empirical separation of total intra-industry trade (TIIT) into VIIT and HIIT is conducted using the threshold method. The empirical results reveal the presence of significant levels of IIT in automotive trade flows between South Africa and its bilateral trading partners. In accordance with theoretical expectations, the empirical investigation signifies the existence of high shares of VIIT dominating TIIT in the South African automobile industry. Moreover, the empirical analysis postulates that, within VIIT, the domestic automobile industry potentially produces and exports high quality automotive products proposing that such VIIT can be partly explained by fragmentation and international production processes. Next, gravity models are estimated to investigate the determinants of IIT patterns in the automobile industry. The econometric results of the gravity models of VIIT, HIIT and TIIT are statistically and economically significant in the context of the fixed effects method of estimation and in accordance with new trade theories. The empirical results reveal that relative difference in economic size, trade openness, foreign direct investment (FDI) and tariffs stimulates VIIT, whilst distance, economies of scale and automotive assistance negatively affect it. Conversely, relative difference in economic size, FDI and automotive assistance negatively affects HIIT, whereas trade openness and depreciation of the exchange rate positively influences it. Thus, the findings of the thesis assert that IIT patterns of VIIT and HIIT in the automobile industry are influenced differently by country and industry determinants, revealing that the theoretical and empirical distinction of TIIT is important. The thesis proposes advancing trade liberalisation and deregulation of the South African automobile industry that could attract greater efficiency-seeking FDI complementary to trade and as a consequence enhance IIT levels.