Board Thread:Game Discussion/@comment-4475421-20160823075252/@comment-27006659-20160823220447

I think what you're hearing is the sound of straight cut gears.

http://rr3.wikia.com/wiki/History#Real_Racing_3_Jaguar_Update_.28v4.5.1.29

Fixes/improvements:
 * Career series now unlock at earlier Driver Levels
 * A Fully Upgraded filter has been added to the Manufacturer Select screen in 'My Cars'
 * Turbo, Blow Off Valves and Supercharger SFX added to cars that have forced induction
 * Improved Transmission whine SFX for racecars