Figure 1-1: Average performance, size and fuel economy of new U.S. cars, 1977-2008, indexed to 1977 averages. Graphic from MacKenzie, 2009 using data from U.S. EPA, 2008 vehicles. Figure 1-2 graphically illustrates four case studies of growth in the mass of vehicles of various classes. 1.2 Motivation Existing work by [An and DeCicco, 2007, MacKenzie, 2009, Knittel, 2009] has in- vestigated the tradeo↵s among performance, size and fuel economy and consumer willingness to pay for said attributes. However, as shown by Cheah in the previous section, vehicles similar in these common metrics may still be substantially di↵er- ent in their ability to deliver functionality to the purchaser in the form of additional features. The need to quantify this tradeo↵ dimension has, to date, remained unfilled. Performing an analysis of vehicle features pays dividends in other ways. While features such as fuel injection, multiple valves per cylinder and variable valve timing 18