Look at the map of Nashville

[Hortensis]

13. Good conjecture, though. RW bombers typically want to kill

or at least create major disruption, preferably with blood. When bombs go off outside arenas and such, missing the opportunity to kill many, it's virtually always because the terrorist(s) screwed up.

(LW bombers are famous with terrorism experts for generally preferring to blow up empty facilities, also for warning ahead of time to make sure no one gets killed. But LW bombers are also comparatively much rarer, especially in this era.)

So just blowing up a vehicle on a dark, mostly empty street also made me immediately wonder if it exploded prematurely, before people were around, or as you speculate, before it was moved to a bigger target.