For most of the automobile's life, functionality has ruled the engine compartment. It has been a dark, greasy place only appreciated by mechanics and other assorted “gear heads.”

To most traditionalists, the idea of introducing any sort of design or aesthetic sensibility to this area might be considered downright frivolous. When powertrain engineers toil long into the night, it's doubtful they're doing it to make a “pretty” engine.

Yet anyone who has ever installed a chrome-plated air cleaner cover or gawked at a tricked-out hot-rod understands that the real estate underneath the hood can sometimes be beautiful.

Automakers are starting to understand this, too, as they strive to give their products — and their powertrains — stronger brand identities. They want owners to believe their new chariot's engine will be virtually maintenance free so they install 100,000-mile sparkplugs at the factory, sealed batteries, and maybe even eliminate the dipstick in favor of an electronic sensor. But they still want you to occasionally pop the hood, if only to enjoy the view of your Northstar, Triton, or H-6 engine.

“For me, it's part of the experience of possessing a car. You lift up the hood and look at the engine and you have fun with the view of the engine: you like it, you love it,” says Hans-Dieter Futschik, a designer at DaimlerChrysler AG's Mercedes-Benz unit, who devotes a lot of his time to making engines look distinctive and attractive.

Luxury carmaker Mercedes-Benz has been paying attention to engine compartment design for 15 years, he says. At first it was more a case of “organizing the chaos” and arranging components so that the engine compartment would crush more uniformly in a crash, but it has evolved greatly since then. Mercedes has “four or five” designers now dedicated fulltime to engine compartment design, Mr. Futschik says, and they even benchmark their designs against competitors.

It probably isn't that surprising that a maker of $100,000 luxury cars with big V-8 and 12-cyl. powerplants is devoting some resources to engine compartment design, along with other blueblood competitors such as BMW AG and Toyota Motor Corp.'s Lexus division. But in fact mainstream manufacturers — from Honda Motor Co. Ltd. and Volkswagen AG to the U.S. Big Three — also are doing work in this area.

Pop the hood on just about any concept car or truck introduced over the last several years and you'll see elaborately designed intake manifolds, valve covers, plastic “beauty covers,” graphics and numerous other details that are painstakingly designed to reinforce the overall design theme of the vehicle — or just make the engine look mean and powerful.

Anything to help further a vehicle's image. In the case of pricey luxury cars, “the look” usually consists of expansive plastic covers emblazoned with company logos that give a maintenance-free look that can help sell the car — and a more expensive engine option.

GM, for instance, spends lots of money advertising its premium “Northstar” engine. It's not going to miss an opportunity to promote it under the hood as well.

Another example is the sporty, performance-oriented “styling” of Subaru's H-6 boxer engine. Here, a little plastic and metal mesh go a long way toward giving the engine a strong, techy look.

And Mr. Futschik emphasizes that Mercedes isn't putting design effort into only its most expensive cars. He says even the engine compartment of the automaker's tiny A-Class peoplemover got some design tweaking.

Some consumers worry that all this fuss over making engine compartments look “better” — including the addition of plastic covers over much of the engine — will make it more difficult to do maintenance and repairs. However, Mr. Futschik says a key part of engine compartment design is to make regular maintenance items accessible, and beauty covers easy to remove.

However, another problem does loom on the horizon, Mr. Futschik says. New regulations coming in Europe that are designed to reduce pedestrian deaths and injuries will force automakers to alter the hood heights and front fascia designs. The result will be less room under the hood for designers to work with.