My husband and I just test drove the Clarity and really liked it! However, when we tried to install our convertible car seat, rear facing, in the back middle seat, we were unable to get a tight install. We have the Britax Boulevard Clicktight which has been an easy rear-facing install in the back middle seat for every other car we've seen. Any Clarity owners have a convertible car seat they were able to install rear-facing in the back middle seat without borrowing the latches from the side seats?
Check with your local fire station and see if they offer assistance in installing and/or confirming correct installation. Ours offered it when the kids were younger and they fixed what I thought was an adequate installation of our rear-facing seat. They said that borrowing the latches from the side seats was not acceptable since they are independent of each other (at least they were in my old car), which may result in too much motion in the event of a crash. We ended up having to use that funky "I"-shaped piece to get a snug fit. Often, the car seat manufacturer will have directions on how to handle the various attachment situations, but the fire station check would be a good double check. Edit to add: Here is a page that has the ability to search for local safety check locations. It is most of the way down the page. Edit 2: They also said that something like 3/4 of car seats are installed incorrectly the first time people try. I definitely would recommend going to a safety check location if you have any doubts and not rely on people on an internet forum, not matter how helpful they are.
I'm surprised you're not able to get a tight install using the Clicktight system, it's the best on the market. As long as you're installing it correctly, you should always get a tight fit. Is the seatbelt path loose before close the seat down? I would try to tighten that to see if that helps. Also, never use the side LATCHs for the middle seat unless the owner's manual say you can. https://content.webcollage.net/apps/cs/mini-site/britaxusa/module/britax/wcpc/1412108905712/tab/demo-1acdb76c?from-pp=&suppress-site-prefs=&showtabs=&enable-reporting=true&wc-target=&channel-product-id=
Your "every other car" probably had seats that had their own LATCH system? I tried to install my son's booster seats in the middle too but "borrowing" from the side seats also didn't work too well (at least not as good as simply having the booster on the side)
We have the exact same Britax Boulevard Clicktight car seat you have. It took me some trial and error, but I ended up with a perfect rear-facing install of the seat in the center using the lap/shoulder belt. I was quite happy with how well it came out. You definitely cannot borrow latch anchors for a center seat install. That would not be safe. I don't believe I've ever encountered a vehicle and car seat combination where you can use the inner latch anchors without compromising safety of the install. There are a number of reasons you could potentially be having trouble with your install. I found the most helpful thing to do, despite me feeling very confident of my car seat installation skills, was to sit down, review the manual in detail, and watch the official Britax installation videos to refresh my memory. I discovered that I hadn't remembered all of the exact steps as well as I thought! For instance, I was attempting to manually activate the seat belt's automatic lock when in fact that is not at all necessary. That was what was causing my install to be ever so slightly crooked (which drove me nuts). The other mistake I made at first was to not route the entire seat belt through the belt path. It'd been over a year since I did the install in our older car, so I forgot and thought I could just route the lap portion of the seat belt through. Just try again, and if you need specific help, feel free to come back and ask. Good luck!
