We've written a lot lately about the environment improvements taking place in heavy-duty diesel engines, including next year's rollout of Tier-4 Final machines, and some of the technologies manufacturers are using to meet these emission cuts. But we haven't talked much about the effect of these changes on machinery styling—for better and for worse.

Before you dismiss this topic—and assume that construction fleet owners could care less about how their machines look—think again. The Tier-4 Final emissions regulation has manufacturers going back to the drawing board, and in their research, many have been surprised to find that contractors, rental fleets and public owners are asking them to design machines with a more modern face and operational feel.

Some of these styling concerns are due to an unintended consequence of clean-diesel engines: Extra pounds. Because many of the engines require bulky aftertreatment devices that take up valuable space in the engine compartment, you might have noticed that machine cowlings have expanded several inches around the engine.

The bulk impedes the operator's view around the machine, so softer body corners, larger cuts of glass in the operator's cab and standard rear-view cameras are some of the tactics manufacturers are using to help the operator see again. This is not just an aesthetic issue, but one of safety, as engine compartments have gotten wider and taller.

Secondly, manufacturers are taking advantage of the opportunity to refresh their brand identities. Many are asking the question, "While redesigning the engine compartment, why not rethink how the overall machine looks?" Product designers also want a machine to be recognizable, but colors and decals may conflict with a machine owner's brand (indeed, some rental companies obliterate the manufacturer's trade dress). This leaves machine design as an empty canvas for OEM branding.

For example, Caterpillar in 2007 began a massive styling exercise across its broad machinery lineup, and the changes are starting to gel as its introduces its Tier-4 Final machines. Some of the details include hexagonal holes stamped around the engine compartment, raked cowlings and chamfered fenders. Grilles now curve around the engine, sporting a honeycomb mesh and recessed eaves that are also functional: The extra surface area helps keep dust from caking up around the radiator.

These various styling cues have not only improved visibility but also helped Cat establish a stronger bond with its customers. A machine is a "billboard to tell the world they have arrived," explains Bill Campbell, product application specialist. "They know we are the premium machine in the marketplace, and if they've got enough money to buy one, they must be doing well."

Updating a machine's design also helps companies like Caterpillar position themselves as making industry-leading products. "There is all kinds of public policy that affects us," says Campbell. "So, we're very sensitive to the public's image of the company."

Inside the cab of many Tier-4 Final machines is a renewed focus on simplicity. Prior to the latest clean diesels, cabs were getting loaded up with buttons, switches and other gizmos that, many times, went unused or were a justifcation to charge a higher price. 

The switch to cleaner diesels—and all the complexity that has come with it—now has manufacturers trying to streamline the operator's experience. This could have the side benefit of making it easier to recruit younger operators, experts say.

We'll be on the lookout for more of this trend at next year's CONEXPO-CON/AGG 2014 show in Las Vegas. Meanwhile, let us know below what you've noticed (or not) in the styling department.