I believe it was Higgins' truck. He had multiple vehicles that he parked at Canton PD.
It's hard to say, but I expect he'll be asked more about why he needed to go there and what he actually did in more detail this time.
Safest, most believeable answer for him? "I had plenty of cans of ginger ale in the Jeep but went to get all the Jameson nips out of my truck and office desk drawers 'cause all the packies are closed by 1:30 am. No way was I hiding a murder weapon!"