Airbags aren’t the only things bolstering car safety nowadays. Backup cameras have been mandatory for several years now. And advanced driver-assistance features like blind-spot monitoring and adaptive cruise controls are rapidly becoming common-place. However, as safe as modern passenger cars are, IIHS studies suggest trucks and SUVs continue to demonstrate some worrying safety issues. And that might be due to some regulation loopholes.

SUVs’ designs can help them with safety and fuel economy regulations

In a recent article, Road & Track discussed several aspects of SUV design. It specifically mentioned approach angle, which is the angle between your front tires’ contact patch and the bumper, AutoGuide explains. It’s tied to a vehicle’s off-road capabilities; without a good approach angle, you’ll be scraping on every obstacle. However, it’s also an important factor for SUV and car safety regulations.

The approach angle is one of several things the NHTSA measures to determine if something is a ‘non-passenger vehicle.’ Nominally, this designation is meant for working or commercial vehicles, like cargo vans. Or vehicles people live in, such as RVs.

However, an off-road-capable vehicle can also be a non-passenger vehicle if it meets certain requirements. One is if it has four-wheel drive. And if it doesn’t, it must have a GVWR of over 6000 pounds, and meet at least 4 out of the 5 following criteria:

• An approach angle of at least 28°
• A departure angle of at least 20°
• A break-over angle of at least 14°
• Running (ground) clearance of at least 7.87”
• Front and rear axle clearance of at least 7.09”

These measurements make for a fairly-decent off-roader. But that’s not the only reason why an automaker could potentially design around these requirements. As we pointed out about Tesla’s Cybertruck, vehicles above a certain GVWR are classified as medium- or heavy-duty vehicles. And they don’t have to report to the EPA, although upcoming regulation changes may rectify that.

However, this also impacts SUV safety. Some safety standards, such as those for the roof-crush test, are looser for heavy-duty vehicles, the New York Times reports. Meaning an SUV classified as a non-passenger vehicle could theoretically legally have fewer safety features than one that isn’t classified as such. The Bollinger B1, for instance, doesn’t have to be crash-tested because of its classification.

Does this mean SUVs are unsafe?

It’s true that the NHTSA doesn’t crash-test every new vehicle, SUV or otherwise, Consumer Reports explains. As with the EPA, it often relies on manufacturers following standardized procedures to generate safety data. But it will sometimes randomly spot-check vehicles to make sure they live up to their claims.

It’s also worth pointing out that SUVs, trucks, and crossovers have created safety concerns as they’ve become more popular. SUVs may have more safety features, but they’re usually focused on the passengers. Pedestrians, cyclists, and those in smaller vehicles are arguably in more danger, due to SUVs’ larger size and weight.

The IIHS has had to increase the severity of its tests precisely because so many large vehicles are on the road. It’s also why the NHTSA is updating its crash tests to include more pedestrian-related categories. And no amount of ADAS features will make up for a driver acting as if they’re invincible because they’re behind the wheel of a large SUV.

But does that mean automakers are deliberating shirking on their SUVs’ safety? No. It’s true that some SUVs, like the Jeep Wrangler, are exempt from certain safety regulations. But that doesn’t mean the IIHS or NHTSA doesn’t crash-test them. The Toyota 4Runner TRD Pro, for example, has the GVWR, angles, and 4WD to be a non-passenger vehicle. But the IIHS still has ratings for it, the same as it does for the passenger-vehicle-rated Highlander.

And that doesn’t mean an automaker can’t go above and beyond the regulations. For example, the Ford Bronco has removable doors, just like the Wrangler. Those doors mean the Bronco is exempt from side-impact testing because removable doors typically don’t have airbags. However, patents suggest the Bronco will offer tubular doors with a kind of built-in airbag.

What about the fuel economy and emissions regulations?

So, if SUV designers aren’t deliberately chasing looser safety regulation targets, what about the fuel economy claims?

Well, according to the IEA, it’s SUVs that are causing the overall growth in fuel consumption. And as the NYT and Car and Driver point out, because SUVs and crossovers have looser CAFE regulations, it’s almost like automakers are incentivized to offer them instead of passenger cars. Plus, Ford offered the first F-150 explicitly to get around fuel economy and emissions regulations of the period.

However, as Car and Driver also points out, automakers pushed back against President Trump’s plans to lower CAFE targets. Partially, that’s because they already had expensive and more fuel-efficient products in the pipeline. But it’s also because consumers demanded more hybrids and EVs.

SUVs aren’t designed in a vacuum. It takes years of careful planning, engineering, and prototyping to finalize every part of the vehicle, including the paint. And it’s all inter-connected. Adding more weight may lower fuel economy ratings, but that weight gain might be due to more luxurious interior materials or extra airbags. That’s how designers and engineers think: what they give up in one area, they may gain in another. And if they know they can cut into fuel economy a bit and not worry about it, that gives them more freedom elsewhere.

So, are SUVs explicitly designed to offer less safety and fuel economy? No. Their mass and height are worrying for pedestrians and smaller-vehicle occupants—but that’s as much down to physics as design. Ditto with fuel economy. Even if the 4Runner had the Mazda CX-5’s powertrain, its shape and size would still make it less efficient.

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