This book provides an introduction to road vehicle aerodynamic design for students, engineers and designers working in the automotive field. A description of the basic mechanisms of lift and drag production on road vehicles (domestic cars, commercial vehicles and track racing cars) is given together with the principles of drag reduction and the generation of downforce. It explains the physical principles and the methods of experimental measurement that can be used in the study of road vehicle aerodynamics. Many of the experimental studies conducted in the previous two decades are described. Wind tunnel and road testing methods are considered and a short introduction to computational fluid dynamics techinques is included. Using the information provided, the reader should be able to attempt a low-drag conceptual design, and should be able to assess the reasons for aerodynamic defects in an existing shape.