Tesla's Model S and X vehicles got a powertrain refresh that boosts their power and range -- in other words, interested buyers will have to choose between the upgrades and the perk. Choosing free Supercharging could still be worth it for those who find a really good deal in the inventory section, though. Especially since Tesla told Electrek that by "free Supercharging," it truly means unlimited use of its charging facilities for the duration of the buyer's ownership.

The automaker also brought back free Supercharging as a referral reward in March, but with terms that are more sustainable for the company. Under the new rewards structure, when someone purchases a Tesla using someone else's referral code, both of them will get 1,000 miles of Supercharging at no cost.