The new Lincoln MKZ is a striking car, but so far it hasn't sold well. Photo credit: Ford Motor Company

Once upon a time, not so long ago, Ford (NYSE: F) owned a whole bunch of different auto brands.

There was Jaguar and Land Rover and Volvo and Mazda and Mercury and Lincoln and even James Bond's favorite ride, tiny British supercar maker Aston Martin.

They're all gone now, sold off during Ford's wrenching restructuring, casualties of CEO Alan Mulally's determination to focus the whole company behind one single line of products.

All gone, that is, except for Lincoln.

Of all of the brands Ford once owned, the only one it kept was an ancient luxury brand started by Edsel Ford -- a brand that in recent years has been known mostly for airport limos.

For a while, I thought I knew why. Just as General Motors (NYSE: GM) is doing with Cadillac, I figured that Ford would completely overhaul Lincoln, turning it into a high-margin, high-profit global luxury-car powerhouse.

GM's overhaul of Cadillac is starting to look legit. But I still don't understand what Ford is thinking with Lincoln.

The change that got things rolling -- only it didn't
I admit that I got excited when Ford put Jim Farley in charge of Lincoln last year. You probably haven't heard of Farley, but inside the auto industry, he's a big deal. Alan Mulally once described him to me as Ford's "secret weapon."

Before Farley joined Ford, he worked at Toyota (NYSE: TM) -- where he was the general manager of Lexus. In other words, he's a guy with firsthand experience running a great luxury-car brand. He seemed like a great choice to turn Lincoln into something special.

But so far, it's not happening, despite a marketing overhaul for "The Lincoln Car Company" that launched in December.

The latest Lincolns are pretty cars, but they're not hitting home runs with critics the way Ford's mainstream cars always seem to do. More to the point, they're not selling. The Ford brand's sales were up almost 7% last month. Lincoln's? Down 22.5%.

It doesn't help that Ford botched the launch of the latest Lincoln, the MKZ sedan, holding up production for weeks because of quality issues -- while a huge national ad campaign was running. Intrigued potential customers visited dealers, only to find no cars.

That didn't help Lincoln's rep with the customers or with its dealers.

Ford's magic has so far eluded Lincoln
Lately, everything that Ford has launched has seemed to be an instant success -- except for Lincoln. Go back through Ford's new-vehicle launches over the past couple of years -- Fusion, Escape, Focus, Explorer. All big hits with critics and buyers. In some cases, Ford hasn't been able to make enough to meet demand.

But where are Lincoln's hits? So far, that new-product magic has eluded Ford's luxury brand. Lincoln doesn't have a single gotta-have product, just a confusing stew of alphabet-soup model names. No car stands out; no car gets big attention.

It's possible that those gotta-have products are coming, of course. It's possible that Ford has a big vision for Lincoln, that the company is quietly laying the groundwork (and making the investments) for a big brand renaissance that will be clear to all of us in a couple of years.

But I don't know. I'm not getting the sense that something like that is happening. And because so much of what Ford has done under Mulally has been excellent, that leaves me wondering what's going on here.

Does Lincoln need a "farewell address"?
Veteran auto journalist David Kiley recently wrote at Autoblog that "Lincoln needs a farewell address," not an overhaul. I'm not sure I agree -- at least not yet -- but Lincoln clearly needs something that it's not getting: a strong new direction, and great new products that work with that direction.

Is it coming? Or should Ford put the Lincoln brand out of its misery, as Kiley argues, and maybe start over with a whole new brand, as Toyota did with Lexus not so long ago?

Scroll down to leave a comment and let me know what you think.

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Fool contributor John Rosevear owns shares of Ford and General Motors. Follow him on Twitter at @jrosevear. The Motley Fool recommends Ford and General Motors and owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.