• Wed. Nov 29th, 2023

Automotive Designer

We'll Leave The Automotive Designer On For You

How Ugly Chins Help SUVs Dodge Regulations

I am fascinated by things that are related to something you’d never expect. Like, for example, the meaningless swirl of hair starting from the crown of your head and working its way out. Hair whorl isn’t actually meaningless, though. It is, for a variety of developmental reasons, significantly associated with sexual orientation. (I’ll wait while you put on a hat, Monsieur Closet Case.)

You won’t fool your doctor about your eating habits, either, Little Mister Diabetic: She’ll take one quick look at the skin tags and dark skin at the base of your neck and know that your blood sugar is out of control. You probably didn’t know those things were correlated. Just like you didn’t realize that the dreaded 28-degree line that’s ruining your SUV’s front end means it was subjected to less stringent crash and safety regulations. We’re talking about approach angle here. Looking at any vehicle from the side, visualize a straight line beginning at the leading edge of the front tire contact patch, then extend this line forward just steeply enough that it grazes the lowest surfaces of the vehicle. That line’s deviation from horizontal, measured in degrees, is the car’s approach angle, the maximum steepness of a ramp that it can approach without making contact with any part of the vehicle.

If this angle cuts a peculiar line into the front end that seems completely out of place with the rest of the design, it’ll result in that SUV overbite. Chances are that line is exactly 28 degrees to horizontal, because 28 degrees of approach angle is the minimum required by law for a vehicle to be considered a “non-passenger automobile.”

2017 lexus nx200t


2017 lexus nx200t


The Lexus NX provides a perfect example of the gawky proportions created by the 28-degree approach angle. Note how the front end comes to a pinched, protruding point, with all the bodywork below the grille angled to conform to the 28-degree line. 2017 NX200T shown.

In typical government style, there’s a list of requirements for this classification, beginning with this comedic gem: An automobile may be designated as a non-passenger automobile if it is designed to transport more than 10 passengers. Please re-read that sentence. I’ll wait for you to stop laughing.

Vehicles can also be considered non-passenger vehicles if they have temporary living quarters, an open cargo bed, or cargo space greater than their passenger volume. This is how the government identifies RVs, pickup trucks, and cargo vans. The reason for doing so dates all the way back to the Sixties, when the government was beginning to toy with introducing emissions standards. Smothering large vehicles with emissions-control equipment would interfere with their ability to carry heavy things like cargo and people. To prevent this, they were classified differently than plain old cars.

So, too, was any vehicle capable of off-highway operation. Likely a concession to farmers and ranchers, this subset of non-passenger vehicles was created at a time when off-road vehicles were so miserable to drive on road that nobody ever did. Of course, that’s no longer the case. The vast majority of “off-road vehicles” are now used for regular transportation.

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.

But why would a manufacturer destroy a car’s front-end looks just to be classified as an off-road capable vehicle? Simple. Remember, off-road vehicles are a subset of non- passenger automobiles, all of which are a subset of a group called “light-duty vehicles.” Since, as defined, these vehicles aren’t meant to carry humans, they’re subject to less stringent safety regulations that help ensure they can perform their farm and hauling duties. They’re also permitted to pollute more. And importantly, they’re allowed to burn more fuel.

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.

For 2017, the last full year for which NHTSA has published CAFE data based on the footprints of actual cars sold, the light-duty target was vastly more lenient than that for passenger cars: 29.4 mpg, which the industry missed by almost 1 mpg. By contrast, passenger cars needed to score a full third higher at 39.1 mpg. That sounds like an unfair penalty for cars, and yet the industry beat it, achieving 39.5 mpg overall. (CAFE numbers are calculated differently than EPA estimates, so these are all higher than what you’d see on a window sticker.)

So the next time you look at a crossover with a 28-degree overbite, know that it cheated on its fuel-economy tests and is subject to more lax safety requirements, because it’s not actually a vehicle designed to carry passengers. Just like the relative length of your fourth finger to your second correlates to testosterone exposure while you were in your mom’s uterus. Who knew?


By admin

Leave a Reply

Your email address will not be published. Required fields are marked *