Your speed drives the engine note, and it plays through the car's speakers. Nothing to install, no account, and nothing you do here leaves the car.
Set it up parked, then just drive — there is nothing to touch once it is running. The speed shown is GPS, not your car's speedometer. Three sounds are free here; the rest unlock with a free code from the Veltor app. The app is free to download and its sounds are free too, so there is nothing to pay. It also reads your car directly over Bluetooth for live dashboards and a launch timer.
Don't worry, it's free. The Veltor app is free to download, sound is free in the app, and the code costs nothing to get. No purchase or account is needed.
In the app, open the Sound tab and scroll to Web unlock code. Type it here. Codes change every hour; once unlocked, this browser stays unlocked.