Parents who have several young children close in age, multiples, or those who carpool with many young kids may not have the luxury of picking a full-sized convertible car seat, which we discuss elsewhere in this report. Space can also be a concern for taller drivers or passengers who need to preserve their leg room in front of convertible car seats.
A narrow seat that is only 17 inches across, the Diono RadianRXT (Est. $270) has won a lot of fans for its ability to fit three across in a back seat. The RadianRXT's other claim to fame is its high height and weight capacities that allow extended rear-facing, even for taller kids: up to 44 inches and 45 pounds rear-facing, and 57 inches and 80 pounds forward-facing. The seat also converts to a booster that can keep kids safe up to 120 pounds. Though it has a 5-pound minimum, experts with CarSeatBlog.com caution that this seat might not fit newborns well.
The RadianRXT offers high-end convenience features like push-button LATCH connectors, but some reviewers still complain about ease-of-use issues. The seat has a lower center of gravity and narrow path for anchoring the LATCH tethers or seat belt, which can make it difficult to route the straps and tighten them, particularly rear-facing. The seat also lacks a no-rethread harness-height adjuster, but the harness tension is adjustable from the front. The cover is machine-washable, but the harness has to be unthreaded to remove it.
The RadianRXT has received very good marks in independent crash testing when used as a harnessed seat. It has a steel-reinforced frame and side-impact protection that is bolstered with aluminum rather than plastic, which reduces seat bulk without sacrificing strength. The seat also offers side-wing head protection, and it can be tethered for greater stability both rear- and forward-facing, which is rare – most seats only allow forward-facing tethering. Like all convertible car seats, the RadianRXT has a five-point harness with a chest clip. Parents should note that the seat only gets fair crash-test marks in booster mode because of concerns over belt placement.
Because it is narrow, the RadianRXT can fit three across in the backseat. But it has a tall shell that can demand a lot of front-to-back room unless you use the Diono Radian Angle Adjuster (Est. $10). The RXT has soft foam padding that keeps kids comfortable and absorbs impact, but it doesn't have armrests. It folds up for easier traveling, but at 23 pounds, it might not be worth it.
If width isn't as much of a concern as front-to-back space, the Maxi-Cosi Pria 70 (Est. $250) is another compact but long-lived convertible car seat, reviewers say. Some models come with a TinyFit insert that makes it a better bet than the Diono Radian RXT for accommodating newborns, and reviewers are big fans of its thick, comfortable padding. Children can rear-face in the Pria until 40 pounds and forward-face until 70 pounds and 52 inches, 10 pounds and 5 inches shy of the Radian. The similar Maxi-Cosi Pria 85 (Est. $300) has an 85-pound limit, but the height limit is still 52 inches.
Experts say LATCH installation of the Pria is mostly trouble-free in part because it has push-button connectors and a recline adjustment handle that is easy to access on the back of the seat. However, some reviewers do wish for a level indicator; the Pria has a simple molded line that indicates the proper installation angle. Seat-belt only installation can be tricky because the seat lacks a belt lock-off, say testers with BabyGearLab.com. The no-rethread harness can be adjusted from the front of the seat, and the seat pad can be washed and dried in the washing machine and dryer – both features reviewers love. There are some complaints that the straps can be tricky to tighten, though.
The Maxi-Cosi Pria gets very good marks for crash protection in independent testing. Safety features include air-filled side-impact head cushions and a "FlexTech" frame designed to better absorb energy in a crash. It has a tether for use in forward-facing mode only, a five-point harness and a chest clip.
Reviewers love the Pria's thick padding and self-wicking fabric, which is designed to keep sweat and other moisture away from the skin. Experts say the TinyFit insert make it a good bet for fitting newborns as small as 4 pounds, but it is only suitable from 9 pounds without the insert. The seat is 19.5 inches wide, 2.5 inches wider than the Radian, so it's not as good of a candidate for parents who need to squeeze three car seats into one row. But it is several pounds lighter at 19 pounds, and experts say its shell doesn't hog as much front-to-back room as similar seats, making it worth a look for installation behind taller drivers or front-seat passengers.
If you need a compact convertible seat on an equally compact budget, the Safety 1st Guide 65 (Est. $90) is a good value that can keep children safe a bit longer than some other lower-priced seats, reviewers say. It accommodates children rear-facing from 5 to 40 pounds and forward-facing from 22 to 65 pounds. The rear-facing height limit is 40 inches, and the forward-facing height limit is 52 inches.
Experts with CarSeatsForTheLittles.org caution that the Guide 65 is not the easiest seat to install. For example, seat-belt installations can be tricky because of a small, finger-scraping belt path. Rolled towels or pool noodles may be necessary to maintain a proper rear-facing recline. You'll also need to rethread straps from the back when adjusting the harness height -- typical for budget seats. The seat cover is hand-wash only, which some parents say is a pain.
However, just like seats three times its price, the Guide 65 gets very good marks in independent crash testing. It does not have a lot of safety extras like those pricier seats, however. You'll get side impact protection, a five-point harness, LATCH connectors, and a top tether -- all standard for convertible car seats. The seat does not allow for rear-facing tethering.
The Guide 65 is 18.5 inches wide, and some parents report fitting three across in a back seat. Experts also say the seat's short shell won't take up too much room front to back, making it a good pick for compact cars. At 14 pounds, it's relatively light for a convertible seat. Most parents are happy with the padding for the price, saying their children seem comfortable, but some caution that their kids' heads slump during naps. Despite the seat's 5-pound weight minimum, experts say smaller babies will not fit properly because the lowest strap slot is too high. However, it has higher height and weight limits than other budget seats, so kids won't outgrow it as soon.