Do you have a Honda Accord (as I do)? If so, check on the weight limitations of the truck lid. I noticed that no one seemed to carry Accord trunk racks - For good reason. I found somewhere references to a 50 lb. limit on the lid and hinges. I also found a couple (not many, though) accounts of Accord trunk lids / hinges being damaged by the bike/rack weight. Note this is highly model-specific. Other cars obviously support more weight, which is a bit strange given how well Hondas are built in general. I really want a trunk mount for my Accord, but it's apparently not a good idea. I hate to spend the $$ on a receiver for no other purpose than a bike rack, as we've already done on my wife's Oddysey.
Just FYI, my $0.02.