Scenario building and forecasting necessarily builds upon the information contained within the exogenous variables and the basic travel behavior equation. In a sense, each exogenous variable must be examined and forecasted separately and ultimately combined with the others for a full understanding of the forecasting model to occur. This chapter deals with this exploration. It presents a series of seven forecast scenarios which have been evaluated in order to both familiarize the reader with the importance of testing movement for each of the exogenous variables, and to provide a set of plausible travel and gasoline forecasting scenarios. The variables chosen for testing purposes are fleet fuel efficiency, real personal income, real gasoline price, and population density. Each scenario is defined by a set of forecasted values for the exogenous variables for the years 1979 through 1985. For the sake of simplicity, only six of the twelve variables specified in the basic CUPR Gasoline Forecasting Model are examined.