After reading the whole thread, I am looking at it this way:
a) The dealership is liable no matter how you slice it. First, the safeguards for the keys to prevent this from happening failed or were nonexistent. Second, whether or not the employee is on the clock, the fact remains that he is a representative of that entity and should be held liable.
b) According to Arizona Revised Statutes, this clown would be charged with Unlawful use of Means of Transportation which is a felony in the state of AZ. As for my home state of IL, it is a Class 2 felony but can also be a misdemeanor in certain circumstances. Unfortunately, Delaware has no such law.
AZ Law:
http://cantorcriminallawyers.com/veh...ng-in-arizona/
Being a car person, whether or not it is the Edge or a ZL1, there would be that sense of violation due to the fact someone decided to take a joyride in my vehicle without authorization. Believe me, I would feel the same sense of anger on a very high level. The OP has a legitimate case against the dealership on the grounds of negligence (bare minimum) and may have to pursue that angle. But the advice of getting a lawyer would be echoed by me.
I understand 130R's points but the basic facts remain that the dealership is still liable due to the fact the car was in their care at the time and safeguards to prevent this failed.