Like many past record-holders, the Italian team had to hypermile (that is, optimize their driving behavior) to keep the P100D going for as long as possible. They drove around Salerno at a pokey 40km/h (24.9MPH) with low rolling resistance tires, the air conditioning turned off and an emphasis on smooth driving techniques (such as the use of Autopilot) that made the most of the battery. All told, the feat took 29 hours — you wouldn’t want to try this if you were in a hurry to get anywhere.
You likely won’t see EVs achieving this kind of mileage in everyday driving any time soon. Tesla officially rates the P100D’s range at less than half this figure for a good reason, since the realities of the road are going to shrink the usable distance. However, the fact that it’s achievable at all is important. It suggests that truly long-range EVs aren’t that far away.