Fitted one to a saloon. Easy enough as said, the holes are pre marked. Just drill though and bolt on.
However there are a couple of differamt designs to consider ime. There are two main mounting points for and aft of the petrol tank on the saloon. Which have to be connected structurally by the tow bar gubbins obviously. The swan neck type I had looks far better from outside the car as the tow bar is semi removable via two bolts, but, this design means theres a metal plate that runs along the floor of the boot under the carpet. This makes the boot floor uneven, but also inter fears with fitting an LPG tank along the back seats.
The type on my car now has the structure on the underside of the petrol tank, but it's not removable in any way and allows the fitting of bike racks to the flange bracket etc. Non removable would appear most practicle, for my purposes at least, but it's dam ugly and a shin breaker.
Then there is the vx factory fit removable job. Expensive I guess, and there the mention of uprated springs on some vx listings. :-/ but I have no experience with this one, or estate models.
Hth.