In Ridge Racer Unbounded, you perform drifts to build up a power bar. Once the power bar is filled up, you can crash into other racers to take them out with a single hit. You can also attempt to take them out normally without the use of the power bar, but whether or not you succeed depends on their health and other factors.
The other use of the power bar is finding key destructible targets in the cities. Once you’ve built the power bar up, your HUD locks onto nearby destructible targets such as buildings you can crash into and drive through, creating a shortcut. Once you’ve created a shortcut, you can use it again whenever you please.
In the video above, the game’s producer discusses how the drifting and power bar work, and you’ll get to see a fair bit of in-game footage as well.