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Electric Vehicles and Roof Racks

January 21, 2024

Electric vehicles (EVs) are becoming more popular as an eco-friendly alternative to gas-powered cars. As EV adoption grows, many owners are interested in outfitting their cars for outdoor adventures and road trips. One useful accessory for EVs is a roof rack. Roof racks allow EV owners to transport gear like bikes, kayaks, skis, and luggage on top of the vehicle. This frees up interior cargo space in the frunk and trunk. But roof racks also impact driving range and performance. When outfitting an EV, owners must balance utility and efficiency.

Roof Rack Styles

Roof racks come in different styles like crossbars or raised side rails. The specific designs are tailored to mount securely and fit the body styling of different EV models.

Crossbars are probably the most well-known roof rack style. These consist of two bars attached laterally across the width of the roof. Crossbars on EVs are often aerodynamic in shape, with rounded edges to slice through the wind. For some small EVs, a single crossbar mounted closer to the back may sufficiently support roof cargo.

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Side rails run longitudinally down the roof on either side. These rails typically have a lower profile hugging closer to the roof’s surface. Side rails can either terminate mid-roof or extend down onto the rear hatch for larger cargo. The sleek, minimalist designs blend well with the smooth futuristic styling of many modern EVs.

Even within the crossbar and side rail styles, there are different configurations and rail heights. Shorter rails place cargo closer to the roof surface. Higher rails lift gear further above the roof, allowing space for items like kayaks or surfboards. The shape, height and positioning can impact noise and drag.

Material Choice

Manufacturers craft roof racks from very lightweight but durable materials to minimize impacts on EVs. Aluminum is the most common, with grades that are resistant to corrosion and bending under load. Carbon fiber is exceptionally lightweight but much more expensive. Many racks incorporate both materials. The clamps and mounting hardware are weather-resistant stainless steel or anodized alloys.

Low Weight is Essential

Keeping roof rack weight down is critical for EVs. Battery packs make electric cars heavier. The battery and electric motor of a Tesla Model 3 weigh over 1,000 lb (450 kg). Adding big heavy cargo to the roof accentuates the high center of gravity. Excess weight also cuts into driving range by consuming more battery energy to haul it around. That’s why shaving off every extra ounce with lightweight aluminum or carbon fiber racks helps maximize EV efficiency and handling.

Weight Limits

When selecting a roof rack, EV owners must check weight ratings. Rack manufacturers specify weight limits based on testing with certain EV models. Attaching too much gear can overload the rack, damage the car roof, or impair braking and cornering.

Weight limits also relate to the vehicle’s roof load capacity. This is the max weight the EV’s body can safely support on the roof while driving. For example, the Audi e-tron electric SUV has a roof load limit of 220 lb (100kg). Exceeding this risks damage even if the rack itself can hold more weight.

Aerodynamic Impacts

Roof racks hamper the aerodynamic efficiency of EVs. The slick sloped shapes of electric cars are designed for minimal drag. Attaching rails and cargo on top interrupts air flow, causing turbulence that the vehicle must push through. This turbulence increases wind noise. More importantly, it also reduces range.

At highway speeds, roof racks can cut range by 15% or more depending on EV model and rack style. The impact diminishes around town, but still exists. Aerodynamic losses are highest with tall crossbars versus lower profile designs. Some EVs like the Hyundai Kona Electric even have a removable roof rack that can snap on only when needed to minimize effects.

Streamlined cargo boxes and bike/ski mounts with tapering shapes help a bit. EVs sacrifice some range and efficiency for the utility of roof cargo capacity – a compromise owners will have to weigh.

Built-In vs. Aftermarket

Some EV models come equipped with integrated factory roof racks. The all-electric Rivian R1T pickup and R1S SUV feature flush-mounted side rails as standard equipment for outdoor adventure. Factory racks fit the vehicle’s styling and have mounts integrated into the body framing for optimal load bearing.

For EVs without provisions, owners can install aftermarket roof racks. These use various techniques to adhere racks firmly to the roof. Adhesive pads bond onto surfaces without drilling, but may not handle heavier loads. Clamping systems cinch under door frames or around roof edges for solid grip without holes. Some kits include protective rubber cushions to prevent paint damage.

Properly installing aftermarket racks involves carefully following directions. Position racks evenly spaced for balance. Tighten clamps or torque roof bolts to specified levels without over-cranking. Run periodic safety checks and re-tighten bolts on long trips. Improperly mounted racks could detach at speed.

Trunk Rack Alternative

As an alternative to roof racks, some companies offer trunk racks for EVs. These attach gear carriers to the liftgate or rear bumper. Trunk racks avoid rooftop aerodynamic losses and center of gravity issues. Cargo stows lower and centered behind the rear axle.

But trunk racks have less loading capacity than roof systems. They also block rear visibility and license plates. For light loads under 100 lb (45 kg), a trunk rack could be a good low-profile option. Going too heavy risks damage to the hatch struts or bumper.

Impacts on Handling and Range

Driving dynamics change when an EV is loaded down with roof cargo. The vehicle’s center of gravity rises up reducing stability. Heavier roof weight increases braking distances. And roof racks harm aerodynamics and cut driving range as mentioned earlier.

How much range is lost depends on the EV model, rack style, cargo shape and highway versus city driving. Range loss could be as little as 10% around town. But expect at least 15-20% less range with roof loads at 70+ mph (110+ km/h) speeds.

EV owners simply have to plan charging stops accordingly. Fortunately, most can use the vehicle’s trip data and range estimators to account for lower range when loaded. A bit less miles between charges is worth the utility gained.

With some smart pre-planning, EVs can handle outdoor adventures and road trips even while outfitted with roof racks carrying gear. The cargo versatility expands possibilities for EV owners. Just be mindful of driving dynamics changes and greater energy consumption. Properly installed racks with reasonable load weights keep EVs safe and fun for adventure.

 

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