DC vehicles have no break in period for the software.... Older cars had a break in period for the transmissions, but this was disabled years ago.

Most cars improve in performance after a few thousand miles due to engine break-in. If you read a lot of car mags- you may have heard them refer to a car as 'green'... meaning it has not yet broke in.

And yes- I feel a difference in vehicles from when we PDI them (inspection done upon delivery from DC) to when we see them back a few thousand miles later.