How Ugly Chins Help SUVs Dodge Regulations

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The reason for that odd overbite on the first generation Lexus NX is explained in this article (it even uses pictures of the NX). In short, it gives an approach angle of 28deg, defining the NX in the USA as an off-road, non-passenger, "light-duty" vehicle.

How Ugly Chins Help SUVs Dodge Regulations

The unappealing overbite of the modern SUV isn't a coincidence.

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Defining the NX (and other crossovers) as non-passenger vehicles allows it to be subject to less stringent safety regulations and alsoo allows it to burn more fuel than a passenger vehicle of comparable footprint (track width and wheelbase). In the end, that allows the automaker to cut development costs.

To be classified an off-road vehicle, a car doesn’t actually have to get Trail Rated. (Much to Jeep’s chagrin, I’m certain.) The first hurdle is that it merely needs four-wheel drive or a gross vehicle weight of greater than 6000 pounds. Then, it must have at least four of the five following characteristics: an approach angle of not less than (you guessed it) 28 degrees, a breakover angle of not less than 14 degrees, a departure angle of not less than 20 degrees, ground clearance not less than 20 cm (7.8 inches), or minimum axle clearance of not less than 18 cm (7.1 inches). With only one wild-card parameter out of five, we begin to see why the 28-degree overbite is so common.

Since 2011, each vehicle’s fuel-economy target is based on its footprint (a multiple of track width and wheelbase length). Subaru could do nothing other than put a lift kit on an Impreza wagon so that it meets four of the five off-road requirements, and voila! The resulting Crosstrek is now a non-passenger-vehicle and given extra credit on the Corporate Average Fuel Economy, or CAFE, test.

 

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simulated “light truck” classfication