The automotive industry is faced with an unprecedented challenge of producing cars that yield more miles per gallon and fewer pollutant. A lighter vehicle means lighter materials which in the same time fulfill safety requirements. In this study, modeling and analysis of the vehicle frame and body have been performed to anticipate the dimensions, weight and percentage of weight reduction when replacing the conventional materials with composite materials. Both steel and carbon fibers volume fractions affected the percentage of frame weight reduction but in an opposite way. The frame deformations under bending or torsion for both steel and carbon fiber composite having the same volume fraction are nearly the same. Boron / epoxy body panels has the least thickness and the highest percentage of weight reduction. Boron /aluminum was found to be a good alternative material for steel box beams used in the integral vehicle structure.