For AirTag tracking the AirTags needs to be in close proximity of an iPhone, so the thief/thieves will need to have iPhones, they would also need to have not disabled the Find My functionality, as it requires that on the phone to connect to and broadcast it's location.
Depending on where they go or stash the car, it may pick up passer-by phones, so you may get a ping from that.
Not knowing the mindset of thieves I'm working on assumptions of two types, those that park it in plain site and leave it for a few days before moving it on, so you may pick up on those. But the types that are more organised with premises or shipping containers in the middle of nowhere would be harder to catch with AirTags.
I think the hardened criminal gangs has ways and means around all this stuff, be it a £40-£400 tracker or a simple AirTag, but they may just be a deterrent for opportunist thieves.