The development of the quality of gasoline and diesel fuel has never been static. It is no longer newsworthy to say that the world of energy and chemical technology is changing fast. However, these changes are so fast that changes in related technology have to advance at the same speed. Consequently it has been a challenging time for analytical chemists in different types of laboratories involved in the analysis of automotive fuel, such as in the analysis of oxygenates in gasoline, to keep up with all the developments. Since gasoline testing is moving into the stage which requires more advanced technology, laboratories need to be equipped to utilise a range of different techniques in order to suit the peculiarities of the different nature of the samples. During the last few years, the volume of gasoline testing by different bodies such as the independent petroleum laboratories has increased. In practice, laboratories are under considerable pressure to implement the designated analytical regulatory methods, and to constantly improve analytical quality. To help resolve these issues, laboratories sometimes turn to instrument vendors for advice on methodological advances in this type of work. The author has been involved directly with the challenges of this work and has experienced the practical limitations of current methods. Therefore the author has aimed to evaluate various analytical approaches in the study of the characterisation of fuel blending additives and, in particular, oxygenates. This work starts out with an introduction about the development of automobile fuel technology and the use of anti-knock additives throughout the period from the early days to the present. Thereafter further chapters review the current methods applied for the characterisation of these type of fuel additives in gasoline, in particular high performance fuels as used in the motor racing industry. The main aim of this work is to evaluate the strengths and limitations of these methods. The thesis then includes a detailed discussion of different analytical approaches encompassing initially micro-elemental analysis for the direct determination of oxygen content. Then follows the most popular method, gas chromatography, which continues to be the key instrumental technique for the measurement of the main parameters of gasoline. Thereafter follows a study of the GC-MS technique. The next chapter discusses the combustion technique using a Laminar burner to investigate the effect of oxygenates on the reduction of the sooting tendency in diesel. The final method under discussion is the estimation of oxygenates using Nuclear Magnetic Resonance Spectroscopy. Each of the above methods has been used on similar types of samples in different categories. Thus the results may be compared and interpreted using the relevant tables, and correlated against each other. The final part of this work has therefore concentrated on the conclusion of the comparative advantages of each method and its reliability. The main samples used throughout this research work have been actual commercial conventional gasolines and specialised fuels. These have been evaluated against a set of reference standards.