In reply to stevieb:
> Thanks. The bikes are all £400 or lower, and the car is 10 years old so not bothered about a scratch or two. Insecure would be a problem though .
With respect, those aren't going to be the lightest bikes.
As Stevieb said, you'll need a rack that rests on the bumper, or it WILL damage the boot lid. My Dad's last car had a dent in it from the rack and my Uncle managed to crack the boot of his old Espace, which turned out to be made of fibreglass. Make sure you get a rack with side straps, to minimise sway. A mate of mine used to put helicopter tape on the attachment points to protect the paint.
You'll definitely need a lighting board because 4 bikes will block the lights and number plate. You can get the electrics done without a tow bar.