For this, I installed a bike rack. It's simple to install and will keep your automobile secure. More information may be found here.  

If you have 'roof rails', you can add the MINI factory roof rack system (base system plus bike modules). But that requires you to lift the bike onto the roof.

The alternative is to add a hitch and use a hitch mounted bike rack. 

I would recommend the hitch and get a 'tray' type hitch mounted bike rack - you will be able to load and remove the bike in a matter of minutes. The only drawback is the price and they are also a bit heavy and awkward to handle when attaching it to the car.

Mini Cooper Trailer Hitch Gen3 F56 F55 F54 F57 F60 (minimania.com)
Mini Cooper Bike Rack Yakima Tray Type Hitch Mount (minimania.com)

Hi,

I have MINI f54 and want to transport our bikes on it for a downhill bike ride but scared of scratches to the car and bikes as well. Can anyone share some good options to transport our bikes securely?