I'm looking for a question to answer in all this....
It would be odd for a car to sit on a lot for 12 months in today's market place. (especially a challenger)
Yes you could save a few thousand on an older model, it depends on the car the dealer and the inventory.
New cars generally don't need a break in period and have no special fluids in them.
Rust from sitting isn't an issue.
The only issue I can think of if it has been on the lot for 12 months is battery life.
All 2012 cars were not built in a day they are built over the entire year
If you have conserns check the build date if it's an early 2011 date ( yep they started building 2012s in 2011)
If the milage is high it may have been a demo car.
Enjoy.