First of all you must choose where you wish to install your bike. There are four bike carrier attachment modes:
The choice depends on:
the characteristics of your vehicle (for example whether it has a tow bar),
the advantages and drawbacks of each of these modes of transport (for example roof bike carrier : advantage = free access to rear door / drawback = difficulty in installing bikes),
the characteristics of the products (for example swinging coupling bike carrier allowing opening of the rear door).
For rear door and spare wheel bike carriers, you must check in the Automaxi guide the reference which corresponds to your vehicle (make, model, year, number of doors).