What happened on crucial second test day in United States

After a day of baseline running, testing ramped up on the Gen3 Chevrolet and Ford Supercars in North Carolina.

Supercars is currently embarking on an historic and critical fact-finding mission in the United States, with two raced Supercars being put under the microscope.

On Saturday local time [Sunday afternoon AEDT time], the two cars completed a second 12-hour day of testing at Windshear Full Scale Rolling Road Automotive Wind Tunnel in Concord, North Carolina.

Where the first day was primarily focused on securing baseline data, the second day focused on trialling different aero parts and settings on the two cars to better understand their effects.

On day one, both the Gen3 Chevrolet Camaro and Ford Mustang spent hours on the Windshear rolling road.

Such was the attention on the first day, that two head aerodynamicists from NASCAR were also on site.

The two cars, owned by homologation teams Triple Eight Racing Engineering [Chevrolet] and Dick Johnson Racing [Ford], underwent a series of changes throughout the second day.

The Camaro was first into the tunnel at 6:00am local time, with a decklid spoiler added after nearly two hours of running.

The Camaro's rear wing position was later changed, before the splitter edge radius was adjusted.

All the while, the Mustang was 3D-scanned ahead of its tunnel time, with the Ford going in at approximately 2:00pm.

After 90 minutes of running, the front fascia adjustment was fitted to the Mustang, before a decklid spoiler was added.

Testing resumed on Sunday local time [Monday morning AEDT]. Keep an eye on Supercars.com for more exclusive content from North Carolina.