Thule Motion 3 XL Rooftop Cargo Box (18 cu ft)

The Motion 3 XL is the premium pick on our rooftop cargo box list, and the reasons are about handling rather than capacity. It holds the same 18 cu ft as the Yakima SkyBox NX 18. What you pay extra for is that every interaction is easier: the mounts tell you when they are tight, the lid lifts with one hand, and the lock will not give up its key until the box is actually shut. If the box goes on in November, comes off in April and gets opened every weekend in between, those details add up. If it goes on for one summer trip, they do not.

Thule's spec page gives 500 L (18 cu ft) in a shell 84.7 x 35 x 17 in outside and 80 x 29 x 15 in inside, a 165 lb load limit, room for 5 to 7 pairs of skis up to 200 cm or 3 to 5 snowboards, and a 51 lb weight. The country of origin is listed as the USA, and Thule's limited lifetime warranty covers defects while excluding wear, scratches, overloading and installation mistakes.

The mounting system is the first thing reviewers mention. PowerClick clamps have a torque indicator built in: you turn the dial until it clicks, and there is no separate wrench to lose, unlike the Yakima's. OutdoorGearLab rated ease of use 8.8 out of 10, the best of the eight boxes in its September 2025 test, and gave the box its top overall score of 80 with an Editors' Choice award as Best Large Capacity Box. Rack Attack's 2026 review adds that the box is designed to sit forward on the roof so the tailgate clears it; Thule lists a front clearance requirement of just over 52 in for the same reason.

The lid is the second. It opens with one hand from either side, and the SlideLock handle shows red until the lid is fully latched; the key cannot be removed before then. BetterTrail found the handle could be worked with two fingers. GearJunkie's 2026 roundup makes the same point from a tall SUV: the handle is reachable from the ground, a strap lets you pull the lid shut without climbing onto the sill, and at 51 lb the box is balanced well enough that its tester installed it alone. BetterTrail measured a 14 in lid opening, two inches more than the Yakima, and a crossbar spread range of 21 13/16 to 36 5/8 in. Inside there are tie-down straps and a reach strap. In BetterTrail's ski test it took three pairs of adult skis of 177 to 182 cm with two pairs of children's skis and poles.

Price class is the obvious one; this is the most expensive of our four picks, and the Yakima delivers the same volume a class down. Weight is the second: BetterTrail's scale read 55 lb 14 oz, about 5 lb over Thule's figure, and OutdoorGearLab lists bulk among its reasons to hesitate. GearJunkie managed a solo install, but plan on a helper for a tall roof.

The finish is the recurring complaint. The glossy black or Titan paint looks like a car panel and scratches like one; OutdoorGearLab and BetterTrail both say it scuffs easily and shows marks more readily than textured shells such as the Yakima's.

Two smaller points from BetterTrail: the mounting clamps protrude farther into the floor than the Yakima's, so long flat items sometimes need shuffling, and the lid occasionally needs a press at each of its three latch points before everything locks. Switchback Travel, reviewing the Low version with the same hardware, found the lid harder to open and close in the cold. At 17 in tall it is also the wrong choice for a low garage; the Motion 3 XL Low, Switchback Travel's overall favorite, gives up 4 cu ft to get down to 14 in.

Rack Attack makes a point that applies to every box here: none is waterproof, because they are vented to prevent mold, and moisture can get past hinges or seals in a severe storm.

Against the Yakima SkyBox NX 18: identical capacity, load limit, warranty term and US manufacture. The Thule has the taller opening, one-hand lid, built-in torque indicators and 5 cm more ski length; the Yakima has the wider 24 to 40 in spread, a scuff-hiding texture and a flatter floor, in a lower price class. Choose by how often you will open it.

Against the INNO Wedge 660: the INNO is for garages the Thule will not enter. It is 11 in tall, opens from both sides and carries skis to about 182 cm, but it holds 11 cu ft. If you need 18, the Thule; if you need to park inside, the INNO or the Motion 3 XL Low.

Against the SportRack Vista XL: the SportRack is a rear-opening budget box for occasional trips, rated for 100 lb. It is not in the same conversation for skiers or for anyone loading from the side of the car.

The Motion 3 XL is the box for the frequent user: PowerClick mounts, a one-hand lid with a proper closed indicator, 200 cm ski room and a lifetime warranty. It sits in the highest price class of the four, weighs the most on a real scale, and its paint will scuff. If those trade-offs read as acceptable, it is the best-scoring 18 cu ft box in independent testing. If they do not, the Yakima carries the same load.