Conspiracy vs. Theory - S17-E5
Plot hole: In order to deactivate the bomb vest, Penelope blocks all cell service in that area. But she reacts positively to the disabling of the bomb back in headquarters, and she keeps talking with the team without restoring cell service.
Chosen answer: Black SUVs are common police, military and dignitary vehicles around the world. It is not too much to assume they could be rented or owned by the police forces in the areas.
kristenlouise3
Other people have explained it but fore more information, federal cars would most likely be brought to the airport from the nearest agency, so they can drive out to their locations especially in rural situations.