This does work and holds a decent amount. I do wish we had bought the bigger size because we're a family of four and we couldn't fit all our luggage in it. So what we ended up doing was putting our clothes in zip up sealed bags that could be suctioned with a vacuum. Unfortunately it did leak when it rained. We went on a 30hr road trip and it rained on us almost the whole 30 hrs and then on the way back home it rained for a few hours. When we got to our destination it was wet inside but being in ziplock bags everything was okay. Beware when using something like this your gas mileage will drop significantly. I drive a 2020 Kia Sorento that typically gets 28mpg on trips and sometimes even 32 but this trip I was lucky to get 20 to 23mpg.

FYI: The extra storage I have on the back was only on from the way home.

Overall it works & would suggest ziplock vacuum bags also you have to fill it up or it'll flop around.

We have a small Hyundai ioniq PHEV, but we have 2 toddlers, an e-bike, an e-trike and tons of toddler and beach accessories and clothes we wanted to take on a 7-hour journey for a 7 day stay. We contemplated renting an SUV, shipping some stuff, buying a bigger car, getting a u-haul, etc. We ended up getting this roof top carrier, a trailer hitch and a hitch cargo carrier instead, and we actually had room to spare. Our friends laughed that it would be impossible in our car, but we did it!

This carrier takes up a tiny footprint when stored in its bag, enough that you could reasonably have it always stored in your car for whenever you need it. But its total volume when deployed is astounding. We put a pack-n-play, a bike trailer, 3 beach chairs, a beach tent, a baby gate, a child bike seat, 2 bags of clothes, a bag of beach toys, 5 towels, 4 bike helmets a bag of board games and 2 foldable strollers up there and we STILL had extra space. We don't have a roof rack so we attached the straps to the door frames with the included strap "adapters" and it was impressively sturdy. We never had a single problem. No sounds, no movement, no leaks, nothing. Only issue we had at first was we let the straps dangle inside the car window, and when it started raining hard it leaked into the car through the straps. Easy solution was to tie the ends outside, problem solved. The straps do not interfere with the door operation in any way.

The only downside to this, that I found, is that it reduced our fuel efficiency. That's kind of expected. I'd estimate this probably reduced us by about 15%-20% for fuel efficiency with another 10%-15% coming from our cargo/trike setup. With about 15 hours of travel time this meant 3 tanks of gas vs the typical 2, or about another $40.

All told, between the hitch, hitch carrier, this cartop carrier, the extra gas and some straps we spent an extra $425 to get everything we needed down to beach. The cheapest weeklong SUV rentals were $1000 and wouldn't even have carried this much. And the best thing is that all of this (except the extra gas) was 1 time costs! Next time we need to travel like this we can do it again for free!

Love it!

Quite literally. We wish we had found this years ago, and we feel very dumb for not having thought to search for something like this before. This product has brought us so much comfort and relief on road trips.
We have a Toyota Yaris, 2 people and a 90 pound dog who takes up the whole backseat. Doesn't leave much room for luggage (you wouldn't believe how efficient I became at packing the car). We were constantly crammed, no matter what, and it made road trips so unpleasant.
We were worried about attaching this bag with no roof rack, but it is completely fine and works great. You do not need a roof rack to succeed with this bag.
We do not recommend the anti slip mat, it seemed to make the bag slide more. We do recommend wiping the top of your car before installation, to remove dust etc. This helps with grip.
This bag holds SO much, even on top of our tiny car. We put most of our luggage in there (except climate controlled or delicate stuff like coolers, backpacks with laptops, etc.) but we could put way more if we wanted to. This bag seems to fit 4 duffles (not the jumbo kind), plus a bunch of other stuff that you can cram between the duffles. We can now move our chairs all the way back, recline them, no more luggage in the way! A miracle for our backs and hips upon arrival!
The bag is very sturdy, reliably water proof if sealed correctly (we have driven through numerous thunderstorms), and easy to attach. It takes a bit of effort to place the hooks under the weather stripping, and adjust the bag, but literally who cares this thing is a lifesaver. Make sure to ensure the weather stripping is sealed back properly so you don't get dripped on in the car when it rains.
We recommend placing two hooks in the front on each side, to hold the bag as it's blown backward while driving, and one or two on each side in the back. No problems this way, it stays on, doesn't sway at all.
We found that as we drove the first few minutes on the highway, the weight adjusts to fall naturally, and the bag strapping may need to be readjusted to put more tension on one side. Not a big deal.
Tie the straps up and tuck them if you can so they aren't flapping and making a racket, or potentially loosening the bag.
Use a lock to seal the zipper, not so much for security purposes, but to ensure the zipper stays shut. I think it would anyway, but it gives me peace of mind to know it won't fly open on the highway. Tuck the lock under the Velcro zipper cover to hold it in place and not put unnecessary stress on the zipper (we have a heavy lock and do not want to misshape the zipper).
Oh, and not to mention, a great price. Most roof rack mechanisms cost hundreds of dollars. It hurts our fuel economy slightly, we fill up slightly more (on a 13 hour drive we may fill one more time than usual, but use only a quarter of that tank).
10/5 stars. Bravo, and hallelujah. I cannot stop raving about this product.

I am actually decently surprised by this bag. I just returned after a 2600 mile road trip with my family from Seattle to Southern California and back. Overall I am satisfied with this product. I got the 15 cubic feet model and strapped it to our 2012 Prius V and it was more than enough space for all our camping gear, pillows, blankets, and eventually dirty clothes bags.

Durability:
Only issue here was when we left to head back home, I noticed a few holes in the underside of the bag. I didn't store anything sharp in it so I am at a loss how they got there. Could have been giant desert spiders or my sister's dog. Either way, it made me think this bag is probably a one time use type thing.

Weather resistance:
I can't really speak to the water/weather resistance as we encountered virtually no rain during this trip except for a brief morning shower at my sister's house in the desert. Everything was dry inside after the rain.

Straps:
I read other reviews that said the straps needed to be tightened every hour or so at the beginning, but this was not my experience. I never felt the need to pull over and check the straps, other than at pit stops. The straps held up even though I averaged 70 mph, with a maximum speed of 80 mph for a few brief stretches. The only notable issue with the straps was after driving through a heavy side wind for about 60 miles, the straps on the side that got hit the most seemed a bit looser. Other than that, no issues with the straps. I really dislike how the hooks go under the weather stripping, which causes an annoying sound as you drive.

MPG:
I noticed this bag produced significant drag, reducing my average MPG from the expected 40 to 34 by the end of the trip. I've done big trips in this Prius before and the MPG has at most reduced to 38 when there's a lot of mountain passes/inclines. So it definitely had a major negative effect on the MPG.

Security:
The little lock that came with the bag (which would stop no one determined to get your stuff) broke instantly when I tried to set a new code, so that was out of the picture. All a thief would need to do is drive up with a pickup truck, quickly cut the straps and shove the bag in his/her truck to get your stuff. It is not very secure. One of the motels we stayed at seemed to be in a not great area so I opted to take the bag off the car and keep it in the room with us. I felt safer with it at other, nicer hotels which had lighting and cameras in the lots.

Overall quality:
I am impressed with this bag considering it was $60. It did the trick. However the major thing this product did for me was make me decide to the bite the bullet and get a roof rack and a large hard shell cargo carrier so the air can at least travel underneath it, reducing drag. Hard shells also seem to be way more secure.

I ordered the smaller of the two sizes of this roof bag because I measure my roof rack for my CR-V and the larger one would have been hanging over the sides of the rails. The smaller one fits nicely in my CR-V Roof Rack. I used the roof bag once recently on a 70 mile trip to Orlando on I-4. Within 20 minuted into my drive after leaving I hit a medium strength rain storm. There is actually a front side to this carrier bag and you want to make sure it's in the front because the backside has a loose flap. When I got to my destination I checked and all seemed dry inside.

I read complaints about the noise people hear when driving down the road. The straps can be tricky to tighten down and they need to be as tight as they can be in order not to hear unwanted noise on your roof. I pulled the wrapped the straps around my roof rack a few times and then snapped the clips in and I pulled pretty tight using my body weight when I tightened it down. On my drive, I hit a bit of a strong sidewind and it was moving my vehicle around a little but, it wasn't too bad. To be honest with you, I never heard any noise while driving and I forgot that I even put anything on my roof until the wind hit me. I was at the hotel for a while and I made a mistake of unstrapping everything. This roof bag takes a lot of patience to strap it down and you want to make sure it's tight.

The Roof Bag surprised me when I first got it and I was worried it wasn't going to fit my coolers in it but, once I got it on my roof and started to load it, I noticed it held my coolers nicely and I was impressed with what the roof bag could hold. It did save me a lot of room.

I didn't give it a full five stars because I've only used it once and it took a lot of patience to tie it down. I didn't have any problems with it falling apart and the wind I hit was strong enough to rip apart a cheap quality bag so, I think it's a pretty good roof bag and for $60, I would recommend it.