We've had one that we've used for about ten years. We've used it for WDW and Myrtle Beach trips from up north. Got it at K-Mart and had to assemble it myself. It's two piece, clamshell type. Holds pretty much. I have to secure it carefully and securely to the roof rack of the van. If the straps aren't really tight, it will make some noises. I am always wary of it being there, but I've never had trouble with it. Haven't ever really monitored the gas mileage because we had to used it no matter how much gas we needed. Some of the newer ones are a lot sleeker than ours. Ours really holds a lot. Usually I put the soft case stuff in it, but I have also used it to transport two golf club sets and then fill around it with beach chairs, beach towels, other stuff that fills in around it. Generally I leave it on for the whole vacation and just drive around with it empty. Shop around. I know we paid under $60 but that was a real bargain. You can spend as much as you like.
