2016 Jeep Grand Cherokee (Fiat Chrysler Automobiles)

If you’re in the market for a new car, there’s a good chance you have looked into at least one SUV. From full-size family haulers, to off-road machines, to compact SUVs – the fastest-growing segment in the market – there are plenty of options of all shapes and sizes. But how did automakers arrive at those shapes and sizes?

In decades past, vehicle styling was limited by design and production methods. But since the advent of computer-aided design and the use of new construction materials and methods, we have entered a golden age for vehicle design. New car and truck styling is only limited by the imagination of designers and the depth of the pockets of automakers.

This has blown many corners of the car industry wide open, including small SUVs. However, while this segment has exploded and there are more “cute ‘utes” every year, the traditional, large, truck-based SUVs continue to exist and are incredibly popular for those that need the added space and towing power. So let’s examine how these various vehicles have gotten their designs.

Born of Trucks

First, you have to understand what SUVs evolved from: military transport vehicles. The military is a place where form follows function; the practical needs of the military determine how a vehicle will look. SUVs like the Jeep Wrangler, Mercedes-Benz G-Class, and Land Rover Defender (a specialty Land Rover not sold in the US) are descendants of these practically designed SUVs. Jeeps trace their roots back to Willys vehicles, which have been aped by automakers around the world. Longer, truck-based SUVs like the Chevrolet Suburban came about before then. Together, these vehicles influenced SUV design for decades.

For almost the entire 20th century, these vehicles influenced other SUVs like the Toyota Land Cruiser, Ford Bronco, and Land Rover Range Rover. Buyers flocked to the confidence-inspiring blocky styling and high-up driving position. According to Robert Casey, retired Curator of Transportation at the Henry Ford Museum, this culminated with the XJ-generation of the Jeep Cherokee, produced from 1984 to 2001. Casey contends that this vehicle was the first sport utility in the “modern understanding of the term.”

In the height of the traditional SUV craze of the 1990s and early 2000s, there was a win-win scenario for automakers and buyers. Buyers preferred the boxy, brawny styling of a traditional SUV, and automakers could deliver those SUVs while making a great profit. These truck-based designs were inexpensive to produce and could net the automaker as much as $10,000 in profit for each vehicle sold. All of this was happening while they were struggling to break even on compact cars.

The Birth of the Crossover

All that changed with the 2000s. As fuel prices rose, interest in massive, hulking SUVs that got 10 mpg waned. Combined with incidents like the Ford Explorer/Firestone Tire scandal, the financial crisis, and the green movement, the traditional SUV market was gutted.

Early crossovers were awkward-but-bold attempts by automakers to deliver enhanced versatility on car- and minivan-based platforms. In response, automakers attempted to develop vehicles with SUV-like qualities but on more efficient and lighter platforms. Cars like the Chrysler Pacifica and Pontiac Aztek were early failed examples of crossovers. However, these efforts lead to the development of extremely competent vehicles based on non-traditional SUV platforms.

It's All About Platforms

2016 Land Rover Range Rover Sport (Jaguar Land Rover North America, LLC)

The platform is the basis of a modern SUV’s design, influencing its length, wheelbase, width, ground clearance, etc. SUVs fall into the truck-based and car-based categories, with a side category for unibody off-road SUVs.

Truck-based or “body-on-frame” SUVs include the Toyota 4Runner, Chevrolet Tahoe, GMC Yukon, Ford Expedition, and Infiniti QX80.

For smaller, car-based crossovers, it is more advantageous to keep production of the SUV close to that of the car, so vehicles like the Toyota RAV4, Ford Escape, and Honda HR-V look like raised versions of their car-based counterparts. This delivers the lightweight construction of the car-based platform, but with a raised ride height.

With modern production methods, automakers can make monocoque or unibody SUVs that are just as capable as any traditional 4x4. The Jeep Grand Cherokee and Land Rover Range Rover are prime examples of SUVs that don’t have traditional body-on-frame construction but can get out on to the trail. The Jeep Wrangler is a body-on-frame SUV designed from the ground up to be an off-road maestro.

They accomplish this with the use of advanced drivetrain systems that can spit power to any wheel using electronic transfer cases, traction control, and electronic limited slip differentials. To achieve the ground clearance necessary to hit the trail, these vehicles also employ active suspension systems with adjustable ride heights. Together, these systems can turn any vehicle into an off-road master.

How Fuel Economy Influences Design

But these vehicles also need to be fuel efficient and are offered with various powertrain technologies, such as variable valve timing, direct injection, and cylinder deactivation. Some are even offered with diesel powertrains. Finally, these big off-road SUVs need to be aerodynamic, so once-square SUVs like the Range Rover, Tahoe, and Suburban have far more rounded front ends than they once featured. Due to an aerodynamic phenomenon called the Kamm-effect, air on a squared-off rear actually exits the vehicle with relative efficiency, meaning large 3-row SUVs can continue to have squared-off rear designs.

The Role of Safety in Design

Safety plays a major role in vehicle design. CAD allows designers and engineers to make the unibody design a solid crash structure. Unfortunately this has resulted in increasingly thick C-pillars (the pillar between the rear passenger side windows and the rear windshield). As a result, sightlines have been greatly impacted, and now new cars must come standard with backup cameras, and almost every automaker offers blind spot monitoring to combat these growing blind spots.

But it’s not all about the occupants. Pedestrian safety laws also dictate that a car can’t be so pointy that it cuts out pedestrians’ legs. In an accident involving a pedestrian, the impact must be spread out over a wide portion of their body to reduce injury.

Like the very first military base utes, modern SUVs are a product of their function. That function has changed from moving troops, to taking folks to their campsites, to bringing the kids to soccer practice in a safe, efficient manner.