Sale has ended but you can still get this app.
Download Vehicle Sounds PRO Now
Vehicle Sounds PRO

Official Description

The app removes ads from Vehicle Sounds application

Procedure of removing ads:
- close the Vehicle Sounds app by pressing back button of android system (not home button),
- start Vehicle Sounds PRO app and press "Remove Ads" button,
- now you can start Vehicle Sounds without ads.

Alternatively you can reboot your phone, then start Vehicle Sounds Pro app and press Remove Ads button.