Nuna PIPA RELX Base: New and Thoughtfully Improved

2020 Nuna PIPA RELX Base: You Can Relax While Installing Nuna’s New Base

One of the challenging things about testing car seats, and especially as a CPS technician who isn’t as active as many of my counterparts here, is that you don’t always catch when a car seat works differently in different vehicles. I always try to test each seat in as many cars as I have available, especially if I suspect that a seat will fit differently in other vehicles, but even then, I am bound to miss some. I literally chose my vehicle because it’s so car seat friendly; it never occurred to me that it would be a professional weakness.

One such case of this has been the Nuna PIPA. I adore the PIPA. I used the PIPA lite with my youngest child until I no longer could because I loved it so (read Katie’s review of the PIPA lite here). I routinely recommend it to people who have the budget to support it. In my Honda Odyssey, the base installed effortlessly. I didn’t mind that the PIPA lite didn’t have a baseless install because installing the base was easier than a baseless install on any infant seat. It was hard to imagine that it could be any other way because for every car I installed it in, that was my experience.

But it wasn’t the experience for every user. Over the years, I’ve heard from a variety of technicians that in some cars, especially luxury vehicles, the PIPA base was a struggle to install. The rigid lower anchor connectors on the base didn’t quite reach the vehicle anchors, or they were at a weird angle, or they left a large gap. The load leg was too long for some low seats, and in others the seat belt tended to bunch in the lock off. Now these were not common phenomena. Most cars had an installation experience like mine, but for those who didn’t, it was pretty frustrating and certainly not how you want to start your car seat experience.

Thankfully Nuna listened. They listened to technicians and families, and they’ve been working for a long time to make a good product better. I got to see the prototype of the RELX base over a year ago, if that gives you any idea of how long Nuna has been perfecting this base, and the effort is met with great reward. The RELX base is a really, really great product. After playing with it for a few weeks, my biggest complaint is that my last baby is 2.5 and I’ll never get to use it.

Let’s dig in.


  • Length: 23.75”
  • Width: 13”
  • Stability Leg Length: 17 positions from 8” to 18”
  • Lower Anchor Positions: The lower anchors protrude 3.5”, 3”, 2.5” or 2” from the base.
  • Weight: 18.5 pounds

The Anti-Rebound Panel

The first obvious, big change the moment you compare the RELX to the original PIPA base is the anti-rebound panel that has been added to the RELX. The back of the base where it contacts the vehicle seat is elevated, which should serve to prevent the seat from rebounding into the vehicle seat in a collision. This is a delightful safety addition; I couldn’t be more thrilled to see it added.

The Lower Anchors

The lower anchors on the original PIPA base essentially spun around on a single axis. They couldn’t be extended for deeper anchor connectors, or retracted for closer ones; they could only go higher or lower and as stated before, this didn’t work for every car. The steel-reinforced RELX rigid lower anchors pop out when released from their storage position, extending fully 3.5” out from the base. Once released from storage, the connectors click into place like their predecessor. If the base isn’t against the vehicle seat, you can then push it in towards the vehicle seat to click the base in tighter. Nuna calls this the 5 second True lock™ installation, and it truly is 5 seconds.

There are 4 depth positions (3.5”, 3”, 2.5” and 2”) available on the lower anchors. Nuna allows a gap between the base and the vehicle seat if you’ve clicked it in to its shortest 2” position and there’s still a gap. This is helpful for any unusually shallow lower anchor positioning.

The lower anchors also feature the red/green window to show if they’re properly locked in, which is a nice, simple touch that was carried over from the original PIPA base. The release function on the RELX lower anchor connectors is similar to the original PIPA base where you squeeze two components towards each other on each side to unhook the connectors. It’s easier to access the components than on the original base, though it would still be nearly impossible to accidentally uninstall this base (which, after driving a beloved family member with dementia who once accidentally unbuckled a car seat base 6 times in one day, is a thing I feel strongly about).

The Seat Belt Path and Lock Off

The seat belt lock off has been completely redesigned on this base and is unrecognizable from the original. The original PIPA lock off tended to cause bunching of the belt because of the shape of the belt path and though it wasn’t a safety issue, it was definitely an annoyance for some. On the RELX base there are separate paths for the lap and shoulder belt, which serve to reduce bunching and ensure proper routing. I found it also made it a little easier to tighten the belt before closing the lock off, which is always appreciated. The push button open on the lock off is easy to do with one finger and the lock off secures the belt tightly without a herculean effort to close it like some other lock offs. My only gripe is the way I usually close lock offs (with the palm of my hand) kept hitting the release button and re-opening the lock off. It was clearly user error, but I had to be more thoughtful about my positioning when using the lock off. I tried the base in 4 different vehicles and didn’t find any substantial belt bunching. It was pretty simple to get a rock solid installation in all of them.

The Recline

Perhaps my favorite feature isn’t what the RELX has, it’s what it doesn’t have: a recline bubble. Hallelujah hallelujah. The recline system the RELX base uses isn’t on the bottom of the base like on most infant seats. When the load leg is in use, the bottom of the RELX is smooth (your vehicle seats will be thrilled) and rather than having the recline foot that can be folded in and out, the recline function is on the top of the base. It can be easily adjusted between 4 different positions, even while installed. The first 2 positions are for an infant under 20 pounds (you want the seat as reclined as possible for a newborn) and the last two are for infants 20-32 pounds. Adjusting this is very simple and can be done with one hand if you have giant hands, or easily with 2 hands if you can’t reach. No more uninstalling to add or take away the recline; once you install this, you don’t really need to take it out until the seat is outgrown.

The Stability Leg (Load Leg)

My only gripe about the original PIPA base was that sometimes when I was in a hurry and grabbed the seat out before fully unlocking it from the base, the base would lift up and the stability leg would extend. This would push the back of the base up and cause the seat to be more upright than it was supposed to be. It was easy enough to fix, but annoying nevertheless. The original PIPA load leg was also not compatible in some middle seats because it’s shortest position was just too long to fit. The RELX has solved both of these issues for the better.

The stability leg on the RELX has 3 sections with 17 locking positions available, so no more auto-extension. The shortest position is just 8 inches long, and it extends all the way to 18” long. I’d be surprised if there’s a vehicle the RELX load leg isn’t compatible in because of it’s length (if the manual allows use of a load leg, obviously). The stability leg still has a red/green indicator at the bottom so you can be sure you’ve got the load leg making appropriate contact with the vehicle floor. The RELX has that indicator on the side, so it’s easier to see from outside the vehicle. While we know that the load leg provides a safety benefit by reducing downward rotation in a crash, Nuna has also put a crumple zone within the load leg to reduce crash forces even further. The updates to the load leg have optimized function and maintained the high standard of safety we expect from Nuna.

Those are the features, but the real test is in the vehicle fit.

No great surprise that in my Honda Odyssey it installed in a hot second with either the lower anchors or the seat belt. The base is fairly low profile, which makes taking the seat itself in and out really quick and easy. The release function is on the base as in the previous iteration and I think the release is a little easier to access and use than in the original model.

In our Nissan Rogue (which is an absolute car seat nightmare), it once again installed well with the lower anchors and then with the seat belt in the outboard positions. In the middle seat, which is the trouble spot, I was able to get a very solid seat belt installation. However, I couldn’t use the stability leg. Because the middle seat belt is slightly off center in the Rogue, the stability leg only partially made contact with the hump on the floor and I couldn’t get the indicators to turn green no matter what I did. It’s a bummer, but hardly the end of the world when either outboard position would work just as well. This is only the 3rd or 4th seat I’ve been able to install in the center securely at all, so this should be commended if anything.

I braved society and used a friend’s Audi 5 series for my next trial. I need you to know that I nearly lost my life doing this. This car is a 2-door coupe, I had the front seat moved forward as far as it would go, but every time I leaned my quarantine-enhanced body in the car to install or adjust the RELX, the front seat would try to move backwards to its normal position and crush my body between the front set and the door frame. Anyway, the base installed very easily with the lower anchors. I couldn’t do a seat belt install in this one (see seat crushing explanation), but nothing about the belt geometry suggested it would be an issue.

I also borrowed a friend’s BMW 5 series as BMW was frequently listed as a car type with incompatibilities on the original PIPA base. I don’t think this exact vehicle model is one of the most challenging ones, but my options are a little limited, so this seemed worth trying. The base installed beautifully in the 5 series. My friend, who has 3 kids and is well acquainted with car seats, watched me install it (from a safe distance!) and remarked how quickly and easily the RELX base went in. It truly was a breeze. The seatbelt installation was similarly simple and it was easy to get the RELX secure without any special effort at all in this vehicle.


I can’t test this base in every car. It simply isn’t possible (especially during a pandemic) to access that many different makes and models of vehicles. I’ve tried to capture a variety here: a coupe, a sedan, a minivan, a small SUV (with terrible middle seat belt geometry), all different manufacturers, hoping that if there was a glaring problem, I’d find it. Instead, in each vehicle, the RELX base was able to be securely installed nearly effortlessly. The 5 second True lock™ installation lived up to its name each time. I can’t promise you this base will be the holy grail of easy installations in every car as it was in these four, but I have good confidence that in a majority of cars, it is perhaps the easiest infant base to install that we’ve seen to date. And as (if?) the world becomes safe enough to open back up, I will be happy to update this review with more vehicles as I can access them.

Bottom Line

The bottom line here is that Nuna took a good product, listened to feedback and made it better. The one-touch recline, the lack of a recline bubble, new seat belt lock off and belt path, load leg improvements, anti-rebound component, adjustable rigid lower anchors—it goes on and on. Every piece was carefully crafted to be as user friendly as possible. I would whole heartedly recommend this base (and the accompanying seat) to any family whose budget has room for it.

The RELX base is standard on the PIPA RX and PIPA lite R, but it is compatible with the PIPA, PIPA lite and PIPA lite LX, and can be purchased separately for MSRP of $199.95.


Thank you to Nuna for providing the RELX base for review! No other compensation was provided. All opinions expressed are those of CarseatBlog.