Virtual drivers in math models can design and evaluate the seating package in all classes of vehicles. With the driver's seated geometry constrained by vision and reach to the steering wheel and pedal, seat design is optimized to support all drivers in three back postures to operate the vehicle. The position of each virtual driver model in the seat is calculated from a biomechanical model of seated load distribution with each model represented by functionally correct positions of pelvis and spine as well as the deflected shape of the seated body in a vehicle seat. This geometry is optimized to design or evaluate seats by changing boundary conditions of select variables and functions in the math tool. The math comfort score is calculated from the physical interface between the virtual drivers and the seating package. The weighted sum of scores for all virtual drivers is the population comfort score for the vehicle seating package.To validate this ERL model, seven vehicles were selected from different market segments. These vehicles were driven for two hours on the same highway by drivers who were trained seat evaluators from 1% female to 99% male based on either height or weight. The subjective comfort scores from the drivers highly correlate (r = 0.78) to comfort scores calculated by the software. The high correlation is considered to validate the ERL tool and process. The correlation reported in this paper was considered by the contracting company to validate the ERL tool and process for use. Since the math tool calculates a comfort score that is directly comparable to the subjective comfort score of drivers, the math data identify the same issues 9 to 12 months before building physical seat prototypes for testing. This tool should therefore reduce time to market and reduce development costs.