After showing us its initial offerings for the new BMW Z4 that were limited to a few alloy wheel options, a dual-pipe exhaust system and a new speedometer, Hartge has taken one step further by releasing a new set of upgrades for the hardtop roadster.For the exterior, Hartge has created a new front apron that covers the air inlets, carbon fiber mirror caps, a discreet boot lid spoiler, a wind
