(FORTUNE Magazine) – Not every bubble, it seems, has burst. The market capitalization of motorcycle maker Harley-Davidson, for instance, is expanding faster than the waistline of a beer-bellied biker. Its shares have shot up from $35 in April to $50 today, giving the company a price/earnings ratio near 40 and a market cap of more than $15 billion.

When you park Harley next to other vehicle manufacturers, that starts to look a little rich. Take General Motors: Its global auto operations are valued at $20 billion (after stripping out Hughes Electronics, which is for sale). That means investors pay only $2,328 for each Chevy, Caddy, or Buick sold last year, vs. $66,279 for a Harley Softail or new V-Rod. True, Harley netted $1,922 on each sale in the second quarter, while GM made only $292 per unit. But then GM's margins are plenty fat when it comes to dividends: It pays $2 a share, vs. 12 cents for Harley.

Despite the jump in share price, investors continue to hop on board, citing the luster of the Harley name, the loyalty of customers, and the company's ability to keep boosting production without satiating demand. So strong--and consistent--are Harley sales that analysts have elevated the stock into the ranks of recession-defying luxury names like Tiffany and Four Seasons. Some project earnings will roar ahead at a 20% annual clip over the next five years, vs. just 5% for GM. Writes Merrill Lynch's Hayley Kissel: "The pride of owning a Harley-Davidson is the pride of owning an American icon, with a cachet that is found in very few products, particularly ones that average a little more than $15,000."

But can that pride overcome a dwindling bank account? With layoffs mounting and and consumer debt at record levels, a Harley becomes an eminently deferrable purchase--even for customers with the logo tattooed on their chests.