For release: Jan. 13, 2008, 11:30 a.m. EST (embargo has been broken by other outlets) HX CONCEPT PROVIDES VISION OF A RUGGED, OPEN-AIR HUMMER -Youthful, open-air entry-level-size HUMMER -Designed by a trio of young designers -Convertible body with removable roof panels and modular rear roof assembly -Easily removable fender flares and doors -Full-time 4WD with front and rear locking differentials -Aeronautically inspired interior with functional, lightweight design elements -R