From Erin Glover on the Disney Parks Blog:
In the normal development process of any ride-based attraction at Disney Parks, Imagineers spend weeks and even months testing the ride vehicles. Many of you may have seen one of the first ride vehicles, which was on display at the D23 Expo in Anaheim this past weekend in the Parks & Resorts Pavilion. While it might be a while before you see this or any of the other ride vehicles racing around Ornament Valley, keep checking back with the Disney Parks Blog for the latest updates.
AWESOME!