Most Subaru owners look into a cargo box when interior space runs out. Road trips, camping gear, and winter travel add up quickly on a Crosstrek, Forester, or Outback.
How it feels in use depends on the vehicle. Roof height, crossbar spacing, and hatch clearance all affect fit, noise, and usability.
This review focuses on real-world use once the box is installed and loaded, not ideal setups.
The goal is simple. Understand how it fits, how it packs, and how it feels day to day.
Overview: What the Thule Motion XT M Is Designed For
Where the Motion XT M fits in Thule’s cargo box lineup
The Motion XT M sits in the middle of Thule’s lineup. It is positioned above entry-level options like the Force series and below premium models like the Vector.
Compared to entry-level boxes, it is more aerodynamic, quieter at speed, and easier to use day to day. Compared to premium models, the main differences are in materials and finish, not core function.
For most buyers, it is the practical middle ground with better usability than budget options without paying for premium styling.
Why this size is popular with Subaru owners
This size works well on Subarus because it balances storage with everyday usability.
It adds enough space for travel bags, camping gear, or skis without pushing height too far or complicating fitment. On models like the Forester, Outback, and Crosstrek, it usually fits within the usable roof length while maintaining hatch clearance.
Larger boxes add capacity but are more noticeable. Smaller boxes are easier to live with but can feel limiting.
For most Subaru owners, this size is the practical middle ground.
Typical uses for a mid-size cargo box
A mid-size cargo box works best when you need extra space without going oversized.
It is well suited for road trips and luggage overflow, freeing up room inside the vehicle. It also works well for camping, keeping bulky or dirty gear out of the cabin.
In winter, it helps keep bags and gear dry and protected from snow and road spray.
For most trips, it adds useful space without the added height and tradeoffs of larger boxes.
Recommended setup (for most Subaru owners):
- Motion XT M → balanced size for everyday travel
- Motion XT L → better if you regularly carry bulkier gear
- Thule WingBar Evo crossbars → easier positioning and fit
Key Specifications and Dimensions
What the key specs mean in real use
The Motion XT M offers about 400 liters of space, enough for travel bags, camping gear, or a few pairs of skis without going oversized.
Its exterior size fits well on most Subarus while still allowing proper placement for hatch clearance. Inside, usable space is centered due to taper at the ends.
At around 38–40 lb, it is manageable to install with two people. Load capacity still depends on your vehicle’s roof rating, so packing light and centered matters.
The PowerClick system makes mounting quick, and the SlideLock ensures the box is fully closed before locking.
Overall, the specs translate to a setup that is easy to mount, fits well, and handles typical travel gear.
Key specifications at a glance
For a quick check, these are the specs that matter most when deciding if the Motion XT M fits your vehicle and gear.
| Specification | Motion XT M |
| Capacity | ~400 liters (14 cu ft) |
| Weight | ~38–40 lb (17.5 kg) |
| Exterior dimensions | ~69” L x 36” W x 17” H |
| Internal dimensions | Tapered, widest at center |
| Max ski length | ~155–175 cm (depending on fit) |
| Load capacity | Up to ~165 lb (vehicle limit applies) |
| Mounting system | PowerClick quick-mount |
| Locking system | SlideLock (auto-lock when closed) |
This size works well for most Subaru setups, offering enough capacity for typical trips while staying manageable in height and fitment.
How the Motion XT M Fits on Subaru Vehicles
Crosstrek fit considerations
The Crosstrek’s shorter roof limits how far the Motion XT M can be positioned.
To maintain hatch clearance, the box usually needs to sit further forward, which depends on crossbar spacing and mounting adjustment. With limited adjustment, it can end up too far back.
Because of the shorter roof, balance matters more. Keeping the box centered between the crossbars helps with stability.
It can fit well on a Crosstrek, but placement is less forgiving than on larger Subarus.
Forester fit considerations
The Forester’s taller roof changes how the Motion XT M feels in daily use.
With the box sitting higher, wind noise is more noticeable at highway speeds. Height also makes loading less convenient, often requiring a small step to reach the center.
Fitment is generally straightforward, but overall height and access are the main tradeoffs.
Outback fit considerations
The Outback’s longer roof makes the Motion XT M easier to position.
There is more room to move the box forward, which helps maintain hatch clearance while keeping it balanced. Placement is generally more forgiving than on smaller Subarus.
Hatch clearance should still be checked, but most setups allow full opening when positioned correctly.
In real use, the Motion XT M fits comfortably on an Outback with fewer limitations.
Crossbar compatibility
The Motion XT M works with both factory and aftermarket crossbars, but adjustability affects placement.
Factory bars usually fit but can limit forward positioning, making hatch clearance more sensitive.
Aftermarket bars allow more spacing flexibility, making it easier to center the box and maintain clearance.
More adjustment range generally makes the setup easier to get right.
If you’re working with limited adjustment on factory bars, switching to aftermarket crossbars makes placement much easier.
- Subaru OEM crossbars → direct fit, but limited adjustment
- Thule WingBar Evo → more flexibility and easier positioning
- Yakima JetStream → similar performance with a different mounting style
Storage Capacity and Real-World Packing
What actually fits inside
The Motion XT M works best with soft, flexible gear.
It easily holds duffel bags, jackets, and standard luggage, with room for smaller items. Camping gear like sleeping bags and tents also fit well when packed in soft bags.
Because the interior tapers, bulky items like hard bins or large coolers are harder to fit. The most usable space is in the center.
In real use, it handles typical travel and outdoor gear without feeling cramped.
This box works best when you pack with soft gear instead of rigid containers.
- Thule GoPack duffel set → sized to fit cargo boxes efficiently
- Standard duffel bags → flexible and easier to pack around the taper
Interior shape and usable packing space
Usable space is not just about volume. Shape and opening width matter more in daily use.
The Motion XT M tapers at the ends, so most usable space is in the center. This works well for soft gear but limits bulky or rigid items.
A wider opening also makes loading easier, especially when mounted on the roof.
In real use, a well-shaped interior is easier to pack than a larger box with less usable space.
Using smaller, flexible bags makes it easier to take advantage of the center space.
- Packing cubes → help organize smaller items
- Soft-sided storage bags → easier to fit than bins
Gear types that work best in this box
The Motion XT M works best with soft, flexible gear.
It fits duffel bags, travel luggage, and camping gear like sleeping bags and tents. In winter, it handles jackets, snow gear, and skis well.
Rigid items like bins or large coolers are harder to fit due to the tapered shape.
Installation and Mounting Experience
How the PowerClick mounting system works
The PowerClick system uses clamps that tighten around the crossbars from inside the box.
The knob clicks when the correct tension is reached, removing guesswork and ensuring a secure fit.
In real use, it makes installation quick and consistent.
Installation time and difficulty
Installation usually takes about 10–20 minutes.
Two people make lifting and positioning easier, especially on taller vehicles. One person can manage it, but it is more difficult.
In real use, most effort goes into getting the box onto the roof.
Removing and storing the box between trips
At around 38–40 lb, the Motion XT M is manageable, but its size is the main challenge.
Two people make removal easier and more controlled. Solo removal is possible but less convenient.
Storage requires enough wall or ceiling space due to its length.
In real use, handling the size and finding storage space matter more than weight.
Storage becomes easier if you plan for it ahead of time.
- Wall mount storage rack → keeps the box off the floor
- Ceiling hoist system → useful if you remove it often
Everyday Usability
Dual-side opening access
The Motion XT M opens from both sides, which makes daily use easier.
You can load from either side, which helps in tight parking or when one side is blocked.
In real use, it simplifies loading and unloading.
Locking and closing system
The Motion XT M uses Thule’s SlideLock system to manage both closing and locking.
The lid only locks when it is fully closed, which helps prevent partial closure. You get a clear confirmation before removing the key.
In real use, it reduces guesswork and makes it easier to secure the box properly.
Loading height on taller vehicles
On taller SUVs like the Forester, loading height is more noticeable.
Reaching the center often requires a small step, especially for frequent use.
In real use, height affects usability more than fit.
Noise, MPG Impact, and Driving Comfort
Highway wind noise
Wind noise is one of the first changes you notice with a cargo box.
Shape matters most. Lower-profile, tapered boxes are quieter, while taller or more squared designs are more noticeable.
In real use, aerodynamic shapes are easier to live with on longer drives.
Fuel economy changes
A cargo box usually lowers fuel economy, mainly at highway speeds.
Lower-profile boxes reduce the impact, while taller boxes create more drag.
In real use, the drop is modest and returns to normal when the box is removed.
Stability and crosswind behavior
A cargo box adds surface area, making the vehicle more sensitive to crosswinds.
At highway speeds, you may notice slight movement, especially with taller boxes. Lower-profile designs feel more stable.
In real use, the effect is manageable but more noticeable in wind.
Motion XT M vs Other Motion XT Sizes
Motion XT M vs Motion XT L
The main difference is length and capacity.
The L offers more space for bulky gear and longer items, while the M is easier to position, especially on shorter roofs.
The added length of the L makes hatch clearance and placement more sensitive. The M is easier to center and live with day to day.
In real use, choose the L for maximum space, and the M for easier fit and usability.
Motion XT M vs Motion XT XL
The main difference is size and capacity.
The XL offers more space for family trips and bulky gear. The M is easier to position with fewer clearance concerns.
The XL adds more height and is more sensitive to placement.
In real use, choose the XL for maximum space and the M for easier day-to-day use.
Motion XT M vs Alpine version
The main difference is shape.
The Alpine is longer and narrower, built for skis and other long gear. The M is shorter and wider, making it easier to pack luggage and mixed gear.
The longer Alpine shape is also more sensitive to placement and hatch clearance.
In real use, choose the Alpine for long gear and the M for general travel.
Motion XT size comparison at a glance
This quick comparison shows how each size differs in real use.
| Model | Capacity | Box Length | Ideal Use Case | Vehicle Fit |
| Motion XT M | ~14 cu ft | Mid-length | Everyday trips, mixed gear, easy fit | Works well on most Subarus |
| Motion XT L | ~16 cu ft | Longer | Bulkier gear, longer items | Better on Forester, Outback |
| Motion XT XL | ~18–22 cu ft | Longest | Family travel, max storage | Best on larger roofs (Forester, Outback) |
| Motion XT Alpine | ~16 cu ft | Long and narrow | Skis and long gear | Works best with careful placement |
In real use, the M is the easiest to fit and live with, while the L and XL add space with more placement sensitivity. The Alpine is best for long gear rather than general storage.
If you’re deciding between sizes, it helps to check current pricing and availability:
- Motion XT M → easiest to fit and live with
- Motion XT L → better for bulkier gear
- Motion XT XL → best for maximum storage
- Motion XT Alpine → better for skis and long gear
Pros and Limitations of the Motion XT M
Where the Motion XT M performs well
The Motion XT M stands out for its balance of size, fit, and usability.
It offers useful storage without adding unnecessary height or fitment issues. The aerodynamic shape helps reduce wind noise, and the mounting system makes positioning straightforward.
In real use, it is easy to install, easy to live with, and fits well on most vehicles.
Situations where a larger box might be better
A larger box makes sense when you regularly need more space.
This includes family trips, bulky gear, or longer skis and multiple sets of winter equipment.
The tradeoff is added height, more noise, and more sensitive placement.
In real use, choose a larger box if you consistently need the extra capacity.
Situations where a smaller box might make more sense
A smaller box makes sense when fit and clearance are the priority.
It is easier to position on shorter roofs and helps maintain hatch clearance. It also reduces height for garages and low-clearance areas.
In real use, it works best for lighter storage needs and simpler setups.
Who This Cargo Box Is Best For
Subaru owners who want balanced storage
The Motion XT M is a good fit for Subaru owners who want extra space without added complexity.
It handles everyday travel like luggage and weekend gear while staying manageable in height and fit.
In real use, it adds storage without making the vehicle harder to live with.
Families who need extra luggage space
The Motion XT M works well for families who need more room on road trips.
It moves luggage out of the cabin, improving space and comfort without adding excessive height.
In real use, it adds enough capacity for multi-day trips while staying manageable.
Drivers who leave the cargo box installed frequently
The Motion XT M works well for drivers who keep a cargo box on most of the time.
Its aerodynamic shape helps reduce wind noise and drag, making daily driving more comfortable.
In real use, it adds storage without making the vehicle feel cumbersome.
FAQs
Does the Motion XT M fit a Subaru Crosstrek?
Yes. Fit is tighter due to the shorter roof, so forward positioning is important for hatch clearance.
Will the Motion XT M block the rear hatch on an Outback?
Usually no. The longer roof allows forward placement, which keeps the hatch clear.
How much gear fits inside the Motion XT M?
About 14 cu ft. Enough for duffels, luggage, and camping gear. Works best with soft items.
Is the Motion XT M difficult to install alone?
Not difficult, but easier with two people. The main challenge is lifting it onto the roof.
Does the Motion XT M create wind noise on the highway?
Some. It is quieter than boxier designs, but still noticeable at speed.
Can the Motion XT M stay on the roof full time?
Yes. Expect some added noise and a small drop in fuel economy.
Final Thoughts
The Motion XT M works because it stays balanced. It adds useful space without pushing height, fitment, or daily usability too far.
There is no perfect setup. Larger boxes add capacity but bring more tradeoffs. Smaller boxes are easier to live with but more limiting.
The right choice depends on how you use your vehicle. Mixed travel and everyday use favor this size. More gear or more constraints may push you larger or smaller.
From here, it comes down to your vehicle, your gear, and your trips. That is where more specific comparisons and setup guides help.
If you’re comparing options, it helps to look at size and fit side by side.
- Motion XT M → balanced choice for most setups
- Motion XT L → more space with tighter fitment
- Motion XT XL → maximum capacity for larger vehicles
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