Supposedly rental car companies keep their cars an average of 13 months and are constantly turning over their fleet. This order is over at least a year, so I imagined it's just that they will be buying Model 3's instead of whatever else. The advantage is their service costs and depreciation will be greatly reduced and they can keep the Tesla's 2-3x longer before needing to replace them. This should be a huge reduction in their costs. I would guess they buy their cars with debt anyway, so not like they need to plunk down $4b all at once.
In addition, the rental car companies sold more of their fleet than typical during the pandemic to help ride-out the large decrease in business. As travel continues to pick up they need to replenish their fleets anyway. Finally it isn't a great time to be buying cars in general, so the penalty of buying a Tesla vs another car is lower now than it typically would be.
