i have a rack that is about 15 years old, called an "enflite". it holds 2 bikes, mounts on TOP of the trunk, and takes about 30 seconds to 1 mimute to attach or detach.
you have to remove the front wheel, and stash it in your car (back seat for me), or strap it to the rack. some dont like this design, but i do, for several reasons:
it is a simple design, using quick releases and nylon straps, which are easily replaced. it places the bike on top of the trunk, so if you are lightly rear-ended (the most common auto accident, last time i checked) your bikes wont be trashed. it holds the bikes lower than a roof rack, so you dont have to worry about damaging them pulling into the garage. it is light, and mine even disassembles in half to make it even smaller. it holds the bikes very securely--the bikes dont swing around like on a regular trunk rack.
the only negatives i can think of are: you have to take off the front wheel, but, you can use a bungee to lash it to the rack. you cannot easily access the trunk--but i have rear seats that fold down to allow access. it only holds 2 bikes, but i think there may be a new version that holds 3.
the new version is made by Draftmaster. i think it is draftmaster.com
good luck,
Bob