Since EMD wanted the new locomotive to be visibly modern and updated, they turned to the GM Automotive Styling Center at Troy, Michigan for help. The automobile stylists created the GP30's trademark "hump" and cab roof profile. The hump-like bulge started at the front of the cab and enveloped the air intakes for the central air system and the dynamic brake blister. Units ordered without dynamic brakes were the same shape, but lacked the intakes to cool the dynamic brake resistor grids.