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The Ford P2000 prototype vehicle represents Ford Motor Company's commitment towards environmental stewardship through high fuel efficiency and low tailpipe emission. Low aerodynamic drag coefficient (Cd), weight reduction, and power train efficiency improvements are required in order to accomplish the overall fuel economy target. The objective of this study is to establish an aerodynamic efficient body shape (Cd = .20) that meets the cost, weight, styling, package and fuel economy targets. Furthermore, this vehicle must be able to be operated and manufactured. A new computational fluid dynamics (CFD) method based on a lattice gas approach was piloted for developing and evaluating body shape design alternatives in support of the P2000 PRODIGY aerodynamic objective. Wind tunnel tests were performed to further explore the aerodynamic opportunities that are beyond the capability of the computational method as well as validate the CFD prediction.

There is little information in the technical literature about the dependence of drag coefficient, CD, on aspect ratio (height/width) for car and truck aerodynamics. Some of the information suggests that CD should increase with aspect ratio as the flow over the body becomes more two dimensional. Recent tests of candidate shapes for a commercial van with various roof heights suggested the opposite is true; the taller vans had lower drag coefficients. This report discusses the results of several experimental investigations to examine this relationship. Scale model and production drag measurements of commercial vans are presented along with drag measurements of simple shapes. The shapes consisted of eight radiused rectangular boxes of constant length and frontal area, but with different height/width ratios. The effects of underbody roughness and bumper presence were evaluated and are discussed.