Creative director Ralph Fulton said it will launch without tokens, the franchise's in-game currency used to unlock cars by spending real world money.
"The approach we've taken is that we've designed our game at Playground Games from the ground up to be fair, to be fun, to be rewarding," he told Digital Spy at E3 2014.
"That's incredibly important to us. For that reason, we will launch in September without tokens."
Fulton explained the game's unlock system is designed so players can try out new cars quickly: "We've got an amazing list of 200 plus cars, and we want you to explore it.
"We want to enable you, at very regular intervals, to be able to change your car, pick a new one from the list. If that doesn't work out, you're able to buy a new one really quickly."
He also said that players can gain early access to premium vehicles through a "fruit machine, tombola-style" system as seen in the original's online multiplayer.
"When you do level up, we give you a shot at what we call 'The Horizon Wheel Spin'," he explained.
"We used it in the original in online, and you get to spin and it can be anything from some cash, a load of cash, to a car or to the best car in the game.
"Every time you level up we've got this game of chance, and for the lucky guys, they could be a getting a Bugatti Veyron after playing the game for 30 minutes."
Last year Microsoft's Phil Spencer said the company would monitor microtransactions on Xbox One and adjust models based on user feedback.
Forza Horizon 2 will be set in Southern Europe and offers a dynamic weather system and the same Drivatar artificial intelligence found in Forza Motorsport 5.
It will be developed by Playground Games for Xbox One - and by Sumo Digital for Xbox 360 - for release on September 30.