CONCORD, N.C. (AP) -- -

A six-car NASCAR test at Charlotte Motor Speedway focused on the aerodynamic package for 1.5-mile tracks.

NASCAR had three different configurations that covered seven significant changes at Monday's test. The goal was to help drivers pass easier through more rear downforce or the creation of more turbulent air.

The manufacturers brought two cars each. Ford had Brad Keselowski and Trevor Bayne, Jeff Burton and Jamie McMurray were there from Chevrolet and Toyota brought Denny Hamlin and Brett Moffitt.

NASCAR vice president of Innovation Gene Stefanyshyn said the configurations came from computer simulation and wind tunnel testing, and the ideas needed to be tested on the track.

Stefanyshyn's role at NASCAR's Research & Development Center is on the development of the race cars