Usually when I go camping my car is filled to the top, leaving my passengers with bags between their feet. I decided to make their lives a bit easier by buying a platform that slides in to the tow hitch receiver on my car.
There is a wide variety of platforms you can buy of varying quality, on the low end you get a simple steel platform that has a low lip, and on the high end you can get a $500+ system which has a locking box, can swing away to grant access to the back of the car, and can even be stacked two high.
|Folded-up configuration. It doesn't stick out nearly as far and has a locking pin to keep it from falling down.|
Since I don't plan to use this very often I didn't buy anything super expensive. For about $200 (shipping was extra and isn't cheap) I got a platform that can fold up when not in use. It also came with a anti-rattle hitch tightener and a cargo bag with tie-downs. It sticks out about 3 feet from my car so I have to keep that in mind when backing up or changing lanes
|The flat plate on top with two screws is the anti-rattle hitch tightener, it really works.|
I chose a platform instead of a roof-mounted box or bag because roof mounts negatively impact the vehicle's aerodynamics which can have a significant negative impact on your gas mileage. The hitch mounted boxes and platforms are in the wind-shadow of the vehicle and don't impact fuel economy as much. When driving I didn't notice any impact so I'm sure it is well under 10%, probably 3-5%.
Before you get one of these, thing about how you will use it. Different vehicles have different amounts of weight you can attach to the trailer hitch, the number you are looking for is the "tongue weight" and for cars and small SUV's it is usually between 100 and 250 pounds.
|The bolt and cotter pin keeps it from folding unexpectedly (this is in the down position). When folded up, the bolt goes through the hole on the bottom left.|
I got to use it for the first time when I went camping in Shenandoah and it went well. I put the cooler, the camp chairs, some tarps and a sleeping bag in it and that didn't completely fill it up. This freed up a lot of space inside the car. Driving wasn't affected (except for the changing lanes and backing up, which I already mentioned).
|There is not a body in there, I promise|
You can't just dump your gear on it and go, the stuff needs to be strapped down so it doesn't go flying into the road when you hit a bump. If you have hard boxes you are putting on (like a cooler or Rubbermaid totes you can get tie-downs and strap them directly. I use a soft cargo bag, this has integrated tie-downs and is weather resistant. There is a several inch overlap where it closes and has both a zipper and velcro. It also lets you put odd-shapped or soft items in it (I used it for sleeping bags too since they are somewhat bulky).
|The platform sticks out several feet behind my car, which makes backing up or changing lanes a bit harder.|
As a bonus, the bag it makes it less obvious what is in there so there is less of a chance of someone walking by and stealing your stuff. It isn't real security though, there isn't a lock, and even if you did lock or zip-tie the zippers closed, someone could cut through the bag with a utility knife. You can also buy hard boxes that have a bit more security if you are worried. I would hesitate to leave things in it overnight at a hotel, but for quick bathroom breaks or lunch I think it is a reasonable security compromise.
I'm really pleased with this purchase, although I won't use it very often, it makes my life significantly better when I do.