Today's car designers are taking a cue from the past in creating the automobiles of the future.

And although drawing on the past is not new, more and more automakers are resurrecting models and designs that exited the nation's freeways decades ago.

Among the retro-themed concept vehicles on display at the Detroit Auto Show this week are the Dodge M80, a truck that looks half-toy; the Chevrolet Bel Air, a convertible that aims to revive the 1950s classic; the Dodge Razor, a 1960s-style roadster inspired by the Razor scooter; and the Ford Forty-Nine, a combination of several Ford designs from the 1950s and 60s. 

Another retro-looking car, the Ford Thunderbird, is already in production. The classic has been redesigned to match its once-glorious past, rather than the land yachts with the same name that more recently plied the roads.

"We have such a rich automotive heritage," General Motors Vice Chairman Bob Lutz, whose company is responsible for the Chevrolet Bel Air concept, told the Associated Press. "It's such a gold mine of heritage that can be reached into and updated. It's a very legitimate design direction, and one we are actively contemplating."

Previous Thunderbirds were just two-door versions of four-door family cars that shared only their name with the legendary coupe of the 1950s. But the new Ford model promises to change that, with rounded edges and homages to the original, like the circular rear window and pastel colors.

Nonetheless, the car's new-old look is still only skin deep: the Thunderbird's chassis was developed from the Lincoln LS, a more sedate sedan.

BMW is also cashing in on the craze by bringing back the Mini Cooper long gone from U.S. shores. But the company is distancing itself from other automakers, calling the Mini a redesign of a car that never died.

BMW's Mini spokesperson Bill McHale said the car is new from the ground up, not like the Thunderbird, which rides on the Lincoln LS chassis, or VW's New Beetle, which is built on a Golf chassis. Whatever retro associations are made when buyers see the car is all in the head, he said.

Looking to the past for inspiration has a history of marketing success, said Car and Driver editor Csaba Csere. He pointed out the hugely popular Mazda Miata, introduced 12 years ago, is one of the most successful retro designs.

And while there's no doubt these blasts from the past have a certain panache, are they practical for today's drivers?

Not really, according to Csere, who noted that old styles wasted a lot of space, and said that the drawback has carried over to the remakes. "With the exception of the Chrysler PT Cruiser, most of these cars are not practical," he said.

A case in point is the retro-styled Chrysler Prowler, produced in 1997. This ragtop only has room for two people, and not much trunk space. DaimlerChyrsler, the car's manufacturer, offers an optional $5,000 trailer for those who want more storage space.

But with these limitations, the company has only sold 11,000 units since production began in 1997.

With so many automakers looking to older styles, will everyone be driving these round retro cars in the next 10 years? Not likely, said Csere. He said the fad mostly serves as a magnet to attract prospective customers to their showrooms.

And it works, Csere said, noting how the New Beetle "has polished up VW's lineup." More people now shuffle into VW showrooms to check out their hip collection of cars, thanks in large part to the new bug's eye-catching design.