For most of the history of the automobile, car design showed noticeable progress almost every decade.

And with good reason. Customers love to buy the latest fashions. It’s a key factor that keeps bringing them back to the showroom.

But lately we seem stuck in a rut. Yes, there are some handsome cars out there, but today’s cars don’t look all that different than most models from the 1990s, which were only slightly sleeker than the ones from the 1980s.

Contrast that to the 1930s, when spoke wheels, flat radiator grilles and wooden bodies gave way to streamlined steel bodies with stamped wheels.

Or in the late 1940s, when running boards disappeared and headlamps became fully integrated into the fenders. Or the 1950s, when space-age styling produced chromed sedans with rocket-ship tailfins. Or the 1960s, when low-slung, hard-edged cars provided a clean new look.

The 1970s, of course, gave us federally mandated bumpers that ruined the design of most cars. They looked like boxes with guard rails bolted on the front and rear. But in the 1980s, the industry figured out how to integrate bumpers into the body, and it also started doing flush-mounted glass. This produced more modern-looking designs. But since then, there haven’t been any styling breakthroughs.

It’s not that designers don’t have new ideas. They do. But the conservative nature of this business is holding them back. Auto makers don’t want to risk huge sums of money on truly risky designs. They typically wait for someone else to take the first step.

And yet, has there ever been a better time for daring designs? The auto industry desperately needs to show the public and government regulators that it’s turning out modern cars that are sustainable and safe.

There’s no quicker way for auto companies to demonstrate they’re tackling issues like peak oil prices, climate change and congestion than with bold, modern styling. People will believe the industry is doing something about society’s needs because they’ll be able to see the difference.

Here’s the other thing. Whichever auto maker decides to take the plunge and be the first out with a car that looks hyper-modern is going to create a sensation. The company’s going to be hailed as a true visionary, the industry leader. And once that occurs, everyone else is going to jump on the bandwagon. It always happens that way.

The revolution already has started in architecture. Visionaries such as Frank Gehry and Santiago Calatrava are completely changing our expectations of what buildings should look like. When will the auto industry do the same?

Talk to your designers. I’m just voicing what they privately say among themselves. I know they’re eager to come out with a new look. They want to break free from convention and deliver designs that boldly proclaim, “Now, here is the 21st Century!”

John McElroy is editorial director of Blue Sky Productions and producer of “Autoline Detroit” for WTVS-Channel 56, Detroit, and Speed Channel.