This paper will discuss four wheel drive vehicles of today and tomorrow. It offers those in the light truck industry an awareness of fuel economy challenges and an insight into meeting them. Broad in scope, the text touches on many areas of relevance to vehicle fuel economy. It is concerned with the drive systems of four wheel drive vehicles from the light truck industry and written in the qualitative rather than quantitative style. First, a definition of four-by-four vehicles is provided and then the explanation of the drive systems they use. Next, the paper will cover: 1) Changes in the four-by-four market; 2) the effect of federal regulation on four wheel drive vehicle manufacturers; 3) an overview of E.P.A. fuel economy testing; 4) suggestions for reducing vehicle fuel consumption; and 5) a prototype of a fuel-efficient four wheel drive vehicle.