Changing The Game
Content with gameplay-altering effects, buyable with real money
Time Is Money
Game allows you to pay for speedy/instant access to things that can also be gotten through gameplay
Gran Turismo Sport features an in-game economy system where cars and cosmetics can be purchased with credits. There's no possibility to buy credits with real money. There's no loot boxes, but you get a random car after reaching daily milestones and on some special occasions.
A post-release update included the option to pay for cars with real money. The cars that can be bought are the ones costing not more than 2,000,000.
The game is also mostly multiplayer-centered, so a PlayStation Plus subscription is required to play the entire game.