Can a Vehicle Issued By One Agency Be Used by Another Agency That is Under the Same Umbrella, e.g. Treasury?

I believe the scope of the BPA is limited to needs of the IRS Enterprise Program Management Office.  That excludes Treasury.  So without knowing more, I would say no.  Occasionally someone can make a case that another organization like Treasury has an integral piece of the IRS EPMO needs so funds are transferred to the IRS to acquire the needs of Treasury.  But usually is a stretch though.   

Edit:  I’ll add this for the sake of readers thinking “we do this all the time.”  Yes, agencies do.  They often cite the Economy Act, FAR 17.505-2 as authority as well as some basics out of appropriations and funding legislation including use of intragency funding transfer.  This has gone on for years with little criticism by oversight officials.  But it often isn’t proper.

lawyergirl said:

Whether a BPA issued by one agency can be used by another agency to issue TOs, if both agencies are under the same overall umbrella (e.g., both agencies are under Treasury).

I think formerfed has alluded to the answer to your question.  What does the BPA say about who can place "orders"?