Thule Sonic Alpine Cargo Box

Thule Sonic Alpine Cargo Box

Available Colors: Black or Silver

Manufacturer Specs:

• Volume: 10 cubic feet (283 L)
• Capacity: 3-4 pairs of skis or 2-3 snowboards
• Length: 96”/ 7’ 11” (2.41 meters)
• Max ski length: 216cm
• Width: 27.5” (70cm)
• Weight: 40 lbs (18.1kg)
• Opening: Dual Side
• Locking: yes, central lock

Features:

• Patented AeroNose Design reduces drag and noise making it the most aerodynamic box available
• Patented Rear-Angled Base and expanded vehicle mounting points help maximize trunk and hatch clearance.
• AcuTight Mounting “clicks” when you reach optimal hold to ensure your box is secured to the rack.
• SecureLock™ ensures that all gear is locked and box is properly closed prior to driving

Origin: Designed in Sweden; manufactured in U.S.A., and often in the country of purchase

MSRP: $600

Vehicle: 2014 Jeep Cherokee Trailhawk

Test Locations: Taos, Telluride, Wolf Creek, Western North America

Miles driven: 6,000+ 

Why a Box?

You may be debating between a cargo box and a ski/snowboard rack. After using many different exterior ski racks and enclosed cargo boxes over the years, I’ve opted to stick with enclosed boxes; they keep your equipment clean, secure, and dry, while eliminating the risk of damage, and freeing up more space inside your vehicle.

The disadvantages of an enclosed box tend to be their higher costs, more challenging loading and unloading (due to the extra height), increased noise and vibration, and lower fuel economy.

Fortunately the Thule Sonic Alpine box addresses all of these issues with a new design and a $600 price tag, which isn’t too bad compared to the cost and features of other boxes available.

Design: Exterior

The Sonic Alpine is Thule’s most aerodynamic cargo box. Its low-profile design is intended to reduce wind drag so that the box creates less noise and doesn’t have as much of an effect on the vehicle’s mileage. The box also looks really sleek.

From what I’ve experienced after the first 6,000 miles using the Sonic, the box does what it was designed to do.

Thule’s Sonic boxes all have the AeroNose design, which has a pointed front end to reduce noise and friction. The front of the box also has a dimpled pattern, where drag from headwind is greatest. Like a golf ball, the dimples create turbulence in the layer of air next to the box, resulting in increased stability at higher speeds.

The rear end of the lid acts as a spoiler, overhanging slightly. The Sonic Alpine also incorporates Thule’s new Rear-Angled Base, which tapers the bottom of the box, minimizing the amount of rear overhang while maximizing trunk and hatch clearance. This design provides just enough space to keep my rear antenna on the vehicle and doesn’t hang over my windshield as much.

Design: Interior

The Sonic Alpine’s interior is the same plastic as the exterior, and is not lined. The plastic is strong, impact resistant, and is the same that is used for some whitewater kayaks.

The box has interior fixed straps to hold down skis, but in my experience, they’re not great for efficiently removing skis and are the only thing I don’t like about the box’s design. Fortunately, you don’t have to use the straps, but if you’re concerned about having a single pair of skis sliding around, you could look into finding alternative straps with clips that open and close, or inserting modified foam blocks to hold skis or fishing poles.

The Sonic Alpine comes in either a gloss black or silver finish. I have the black, which I think looks great, though the gloss finish is prone to scratching. I’ve avoided automatic carwashes because of this, opting for a towel wipe down in order to maintain a scratch-free shine.

Installation and Adjustments

The Sonic Alpine is very easy to mount and remove, and can be done in less than ten minutes. The Acu-Tight mounting system uses large knobs that adjust easily and don’t require any tools. The knobs feature a natural slip mechanism (similar to a gas cap) so you don’t have to worry about over-tightening and stripping out the attachment clamps.

Like most Thule equipment, the knobs are designed to work intuitively, easily, and last a long time. The only problem I’ve had is that the knobs are somewhat large (about the size of a fist) and can interfere with loading more than three pairs of skis or wide equipment.

The Sonic Alpine has an expanded mounting range between clamps, allowing for a fore-aft adjustable range of  8”, with a minimum of 23 5/8” and a maximum of 39” between the front and rear clamps. This makes it quick and easy to match the clamps to your crossbars. I mounted the box with a distance of 25” between front and rear clamps to match the distance I’d set between my cross bars.

To allow for more clearance on the rear hatch, the fore-aft adjustment on the Sonic Alpine is larger than most other boxes. When mounting with less than an inch between the rear end of the box and the open hatch on my Jeep Cherokee, I had 16” of windshield overhang. I was also pleasantly surprised by how quickly I could adjust the box’s location along the cross bars, and never felt the box move around or shift on the bars at high speeds or while braking or cornering once the Acu-Tight mounting system was secured.

Capacity

I acquired my Sonic Alpine box primarily for ski storage during winter trips. The box should be able to accommodate skis as long as 216cm, and I haven’t had any issues hauling my quiver of 190cm+ skis around. I typically carry three pairs of skis with bindings and a couple sets of poles with no problems with space or interference with the locking mechanism.

The maximum amount of equipment I’ve carried at once included five pairs of skis + bindings and three pairs of poles. While it required separating two pairs of skis and a bit of adjusting so that the locking mechanism would engage, there were no issues with water leaking or weight capacity. I have also loaded it with full ski bags, however, the height of the large Dakine Concourse bag prevented the box from closing properly.

It’s worth noting that if you plan to store your equipment in above freezing temperatures, moisture from snowy skis resulted in some rusty edges. To prevent this, I open the box slightly when parked in the sun, and my gear usually dries pretty quickly.

Access & Security

The Sonic Alpine box can be opened with a single arm from either the driver or passenger side of the vehicle. Loading and unloading the box can be a bit tricky given the height, particularly on SUV’s and taller vehicles. I find placing the skis next to the box on the cross bars then standing on the rear door jam works best for solo loading/unloading.

The Sonic features a central lock latching system on both sides. This design does not allow the box to open from both sides at the same time. The SecureLock locking mechanism opens and closes easily with the key provided (two keys are included) and requires the box to be closed properly in order to remove the key. When closed, the box cannot detach from the rack.

The hinge points feel similar to those on Thule boxes from 10-15 years ago. Although they are a bit more flimsy than I’d expect, as long as the box isn’t too full, I haven’t had any issues.

Engaging the locking mechanism is usually painless, but when the box is full of gear, there were a few times when I had to shuffle things around to provide adequate clearance for the lock, especially toward the front or rear ends. I never have any issues with ice, rust, or freezing temps despite using the box in a mix of sub-zero temperatures, and in dirty, wet conditions.

Noise and Fuel Efficiency

The Sonic Alpine is quieter than any other box I’ve tried. The sound produced from the wind is noticeable, but not obtrusive.

Most of the noise actually comes from the cross bar mounts rather than the box. I mounted the Sonic to the 53” Aeroblade crossbars attached with the Crossroads Foot Pack. The sound only becomes audible over 40mph, and is equivalent to the sound produced from my interior climate fan on the 3 setting, with 7 the highest. The noise hardly rises to a 4 setting above 60 mph, and like I said, it’s not obtrusive.

Surprisingly, the Sonic Alpine box had very little effect on my fuel efficiency, even with head and tail winds; I only experienced an average reduction of ~0.5 to 1.0 mile/gallon. This could increase on four-cylinder engines or during periods of sustained cross winds.

The maximum head wind speed (vehicle + wind speed) I’ve subjected this box to is ~150mph. When loaded, I did not observe any increased vibrations or changes in the vehicle’s handling.  And if you’re vehicle is long enough to eliminate any over windshield hang, the effects of wind drag on fuel efficiency and noise will likely be even less.

Clearance

The Sonic Alpine’s sleek design also gives it a very low overhead clearance, and the box will reach an additional 11” (28cm) above the crossbars. This box has the lowest clearance of any box I’ve come across, and would be an excellent option if you’re concerned with low overhead ceilings or garage entrances. 

Bottom Line

The Thule Sonic Alpine cargo box is a great way to transport your gear on the outside of your vehicle while keeping your possessions clean, dry, and secure. The Sonic Alpine easily fits 3-4 pairs of skis, and provides space for poles and some excess clothing. I have yet to use it for my summer car camping trips, but I suspect it will be great for transporting tents and sleeping bags while maintaining plenty of cabin space for my passengers and dog.

If you think you’ll need more space, then Thule also has two larger Sonic models, the Sonic XL and XXL, as well as the pricier Hyper XL. But if you’re only looking to haul a typical amount of weekend equipment, the Sonic Alpine is an excellent option if you’re considering style, fuel economy, and price.