I spent some formative years with an accident reconstructionist living and working in the house, and earned spending money organizing car wreck scene photos. Suffice to say, no one ever gets in my car without buckling up and sitting properly. So it was with great interest that we approached Britax with a request for a review unit of their new Frontier car seat, a 25-to-80-pound car seat that converts from a five-point-harness seat to a belt-positioning booster, to evaluate for Z Recommends.

In addition to its harness-to-booster design, the Frontier features significant side impact protection, uncommon in car seats in general and almost unheard of in booster seats. The Frontier keeps kids harnessed up to 80 pounds and 53" tall (standing height), at which point you can remove the five-point harness and use the seat as a belt-positioning booster until up to 100 pounds and 60" tall. This seat has an astonishing usable lifespan of 9 years, which means that the Frontier is truly a second car seat that can transition your child from convertible car seat to a height sufficient for the safest use of shoulder safety belts without the need for a separate booster purchase.

Comparing a seat and separate booster purchase with the the Frontier, we're guessing some parents could go either way, as the Frontier costs a hefty $280 (on sale at Amazon.com for $250 this week). But to understand the seat's additional benefits, you have to understand a bit about why a seat like this exists in the first place, and why it represents a genuinely safer option for most families.

Booster Seats and the Safety Gap

While the safety of kids in cars has advanced by leaps and bounds in the years (decades!) since I was sorting photos of car wrecks, there's been a significant but little-discussed safety gap for four- to eight-year olds in the U.S. State laws are beginning to mandate longer booster use, but still fall well short of regulations in the European Union, where kids stay in boosters until they're twelve years old or 4'5" tall.

Boosters are becoming a popular option for four-year-old and even three-year-old kids in this country. A child typically outgrows their convertible car seat (the backward- to forward-facing step up from an infant car seat) around four years of age, depending on the seat (most top off at 40"). But when that same child is between two and two and a half years old, most of these families have another child, who will likely need a convertible car seat before the first child has outgrown it. So parents suddenly have to choose between buying another convertible (presumably a larger one, so their older child can use it longer) or switching them to a booster at around their third year. New companies and existing ones have accommodated this trend by introducing boosters rated as safe for ever-younger and lighter children, with the smallest belt-positioning boosters now claiming to be safe for children as small as 30 pounds. Images of even younger-looking children on some boosters' advertising and packaging silently encourage parents to switch to belt-positioning boosters as early as necessary to avoid buying another car seat.

But boosters come with some significant safety problems when used with children this young. Seat belt geometry is not as protective for their small bodies as a five-point harness, which better distributes crash forces throughout a child's skeletal body, and lap belts can cause potentially fatal internal injuries in a crash, as children's less-developed hip bones cause the belt to rest against the soft abdomen rather than bone. And even if children are somewhere near the right size or physical stage of development to be adequately protected by a seat belt, it is often far later that they are mature enough to sit in one - that is, not squirming around, getting out of position, or falling asleep and leaning or slouching their way out of the bulk of the belt's protective design. Organizations like the Kyle David Miller Foundation have cropped up to encourage extended harnessing and inform parents of the risks of transitioning to a booster too early.

This means that for most parents, the safest option is to buy a third car seat before eventually shifting to booster use. Such car seats are bound to be the biggest on the market, and more expensive than the least-expensive convertible options were. Some companies rolled out new car seat to booster hybrids beginning a few years ago, but until recently most have topped out at a maximum child weight of 40 pounds for harnessing, meaning that children are forced into the belt-positioning booster earlier than many are ready for it.

A Better Solution: Extended Harnessing

The good news for parents at this crossroads now is that a new wave of car seats that last longer and support a wider height and weight range just might last you through the booster years. Z frequently travels in either of two vehicles, so when she outgrew her twin Britax Roundabouts (one of our top recommendations for convertible car seats) we purchased a Britax Regent for our primary vehicle and a Radian 80 (made by Sunshine Kids) for the other one. In either case, we'll need a booster to get us that extra few inches to 4'9".

I know what you're thinking: The concept of keeping a child in a "car seat" through the age of eight is still anathema to most Americans, but it is gaining traction elsewhere. Enter Britax, which is counting on the idea that belt-positioning boosters that have backs and side wings represent a habitable middle ground for safety-conscious American families.

The Frontier

So we return to our original points about the Frontier: It keeps kids in a five-point harness until they reach 80 pounds or 53" tall (standing height), at which point you can remove the five-point harness and use the seat as a belt-positioning booster until up to 100 pounds and 60" tall. And the seat can be used for up to nine years. Other seats with similar goals include the Graco Nautilus and the SafeGuard Go, both of which also convert from car seat to belt-positioning boosters (boosters with backs).

There are a number of other combination five-point harness/booster seats on the market that are much cheaper - the Eddie Bauer 3-in-1, Graco CarGo, and the Cosco Summit Booster among them. But these seats have harnessing weight limits of 40 pounds, and the Graco CarGo's height limit for harnessed use is 43", factors which seriously limit these inexpensive seats' conversion benefits.

First, we'll take a look at the Frontier's design elements and ease of use, which are one reason we consider this seat a standout product.

We noticed two welcome differences in the seat's design. The first was the seat's width - it is significantly narrower than the Regent, which makes it both easier to move and install and less bulky for use with older children who might be more sensitive to being in a "car seat."

The second is the Frontier's harness adjustment mechanism, which is the simplest and easiest to use that we have ever seen, and we honestly can't see a way it could get much easier. You just pull a tab and gently raise or lower the top portion of the seat. The technique demonstrated in this short video below is all the more astonishing because it was this easy to do the moment we pulled the car seat out of the box; there is really nothing to learn. Contrast this simplicity and adaptability with the belt detachment and rethreading required in most seats.



The Frontier installs in a LATCH system or using a seat belt. LATCH installation is a bit different from other car seats we've installed, as the clips are attached straight down from deep inside the seat footprint, and tightened through twin openings under the car seat's padding; once you get the hang of it, though, it's in some ways easier than accessing LATCH connectors from the outside edge, which often feel displaced by the sides of bulkier car seat models, and it feels good to be tightening the car seat straight down into the car instead of at odd angles that often brace latch connectors against the hard plastic of the car seat.

The Frontier has a couple of captain's chair-like doodads to keep older kids happy - hinged armrests and side-drawer cupholders. We found the cupholders to be less than perfect: they tend to stick a bit and require a certain finesse to get them open, and aren't big enough to hold some of Z's larger travel cups. The armrests are probably of greater interest to older children than someone our daughter's age.

One challenge taller car seats face is the risk of blocking the driver's view behind the vehicle. In this regard, the Frontier performs similarly to its peers; we have heard of some other brands' seats actually hitting some car roofs before they are extended to their full headrest height, but we haven't heard any such reports on the Frontier, and it wasn't our experience, either. Here's a view of our seat seen through our rear-view mirror with the harness at the highest setting; the blockage may look more dramatic because the Toyota Corolla Matrix has ridiculously large blind spots and a small rear window.

The effect is basically that of a somewhat hulking adult sitting in your back seat, except you can't tell them to duck when you're parallel parking.

When your child has outgrown the five-point harness, you remove the harness straps to convert it into a belt-positioning booster. Britax has confirmed that the LATCH system can be used to secure the booster into the car; the safety belt is then needed to secure the child to the booster, but the use of the LATCH system prevents the booster itself from becoming a projectile in the event of an accident when the booster seat is not in use.

Back to Safety: How Does the Frontier Measure Up?

The following chart shows the minimum and maximum weight specifications for each of the three car seat models we consider to be serious contenders in this new hybrid car seat market.

In terms of safety, there are two factors that distinguish the Frontier from most of its competitors: The significantly extended harnessing window, as shown above, and the Frontier's significant side impact protection.

Generally, the upper weight limit of a car seat is not the key factor in considering how long you will be able to use your car seat. Most children will actually reach the height limit well before they will reach the weight limit, so if you want to keep your child harnessed as long as possible, make sure you get the tallest harness system that you can find. Both the five-point harness and booster use window in the Frontier extend slightly longer in terms of height limits as well.

Additionally, there are some differences in the height of the tallest harness slot, even in models with identical height limits; the Graco Nautilus and the SafeGuard Go are both rated for 52" standing (compared to the Frontier's 53") but there's a half- to three-quarter-inch difference in favor of the Frontier in the top harness slot's height. This is worth noting if you have a child with a long torso, and also worth understanding for convertible car seats as well: Children whose height comes mostly from long legs will be able to use a car seat longer than children whose height is in their torso.

The Question of Cost

Britax car seats tend to be among the safest, highest weight-limit, and more expensive car seats in each car seat class they compete in. They also limit discounts and sales to a couple of times a year (this week, Britax car seats are currently running 10% off on Amazon.com and elsewhere). The Frontier retails at $280 ($250 this week), compared with $200 for the SafeGuard Go and $125-$150 for the Graco Nautilus.

This makes the Frontier a significant investment. The question for consumers is, is it worth the extra $80-$100 for the Britax imprimatur?

Britax is a well-funded, heavily research-oriented company; unlike Graco, manufacturer of the CarGo and the Nautilus, they don't make a vast array of kids' products, and don't have any of the black marks (recalls, alleged cover-ups, and massive CPSC fines) Graco has seen in the past decade. And don't even get us started about Cosco, which makes the Summit Booster as well as Eddie Bauer 3-in-1 car seats.

This means the key competitor for this seat is the SafeGuard Go. Both seem like good options, although we haven't had the chance to test the SafeGuard model. We like the emphasis Britax is placing on side impact protection; they are essentially adapting European safety standards for side-impact protection for U.S. use, and have designed this seat to conform with those requirements. We'll get into that this afternoon in an interview with Britax's Advanced Technology Program Manager, Pankaj Amesar.