Over the weekend, Harley-Davidson (NYSE:HDI) capped a four-day gala celebrating its 100th anniversary. We're not talking hog years, either. Harley was born the same year as Ford (NYSE:F), though has been spared many of Ford's cyclical potholes.

When our own LouAnn Lofton took the stock for a test drive back in July, she found it as appealing as the company's signature line of motorcycles. It's hard to argue with Harley's consistency: Double-digit net margins are simply par for the course. The slowest of the past four years had Harley growing earnings by 25%.

The remarkable feat here is that this all happened during an economic slump. A Harley is the only means of transportation for some, but for many weekend warriors and wistful baby boomers, it's a luxury. These big-ticket items are supposed to be susceptible to this kind of slowdown, but Harley's been cruising along nicely.

Investors are in hog heaven. A thousand dollars invested in Harley's 1986 market debut would be worth more than $150,000 today. And while last week's announcement that 2004 models would roll out with extended warranties and slightly lower prices may have some fretting over the possibility that the supply-and-demand dynamics are changing, don't give in.

Sure, this is a response to the incentives offered by car makers like GeneralMotors (NYSE:GM), Ford, and Daimler-Chrysler (NYSE:DCX). Yes, the lure of the 2004 bikes will be pressed to match the 2003 centennial models. But fighting against all that is a strengthening economy. Oh, right, and a company that has proven that it only gets better with age.

Happy birthday, Harley-Davidson!

So did you make it out to Milwaukee to celebrate Harley's 100th or did you live vicariously? How do you think the 2004 models will fare? All this and more -- in the Harley-Davidson discussion board. Only on Fool.com.