Which code is associated with vehicles used for government fleet registration?

The code associated with vehicles used for government fleet registration is GS. This code specifically designates government-owned vehicles, which are typically part of a fleet operated by various state or federal agencies. The GS code helps in identifying these vehicles for regulatory and administrative purposes, ensuring that they are appropriately classified and tracked within the vehicle registration system.

In contrast, the other codes represent different categories: DG is often associated with designated government vehicles or those exempt from certain regulations, RG typically relates to recreational vehicles, and SF could be designated for specialty or fleet vehicles that do not pertain specifically to government use. Thus, the GS code uniquely identifies government fleet vehicles, making it the correct answer for this question.