I've seen two cycle racks on an Alfa Romeo Brera; one on the roof, one on the back. Kinda spoiled the lines but I think you can get cycle racks for most vehicles....

Can get four adult bikes on a Citroen Xantia estate's roof. Halfords economy racks use frame calmps to hold bikes upright and are mounted on model specific Thule roofbars. As above they need to alternate forwards/backwards and in a particular order to avoid clashes between different sized frames. Only required adjustment is to drop one saddle from riding position to lowest.

Pretty sure any medium/large estate or hatch would be same.

Provided you can manage the lifting it's far easier then tailhatch or towbar mounts and retains full access to the boot.