Cybex Solution X-Fix

Only two U.S. booster seats pass a British testing agency's latest side-crash testing (not required by the U.S. government): the Cybex Solution X-Fix (*Est. $210) and Maxi-Cosi Rodi XR (*Est. $150). The Cybex scores slightly better for frontal crash protection, and it has LATCH connectors to keep it anchored to the car when not in use (with other boosters, you're supposed to strap them in with the seatbelt at all times to keep them from becoming a projectile in a crash). Both the Cybex and Maxi-Cosi are belt-positioning boosters, which boost your child so that the vehicle seatbelt fits properly, and both perform this task well in almost all vehicles. However, experts say the safest way to secure your child is in a booster seat with a built-in five-point harness, such as the top-rated Graco Nautilus 3-in-1 (*Est. $160), which converts to a belt-positioner after your child outgrows the harness. The Cybex Solution X-Fix works for children up to 60 inches tall and 100 pounds.

Britain's Which? magazine crash-tests the Cybex Solution X-Fix and also rates its comfort, instructions and ease of installation and use. CarSeatBlog.com doesn't crash-test, but it covers every other aspect of the seat thoroughly and expertly. The Insurance Institute for Highway Safety tests how well the Cybex Solution X-Fix fits in a variety of vehicles, and the National Highway Traffic Safety Administration judges how easy it is to use.