"I had never, ever been associated with something like that. I think it was the most exciting car that I worked on at Ford", says Joe Oros, design director for Ford-brand products back then. His team's long, low, lean European look beat offerings from two other Ford studios to become the winning Mustang design.

Reaction, especially to a car done fast and on the cheap, "was just unbelievable", says Oros, 87, now a sculptor living in California.

The car was launched 40 years ago on April 17, 1964, opening day at the New York World's Fair. It was dubbed a 1964 1/2, though its vehicle identification numbers made it officially a 1965. The coupe started at $2,368, and the convertible , $2,614.

"I will never forget this. The first 500,000 units went out the door at an average of $3,500, 50% more than the car's base sticker, because they (buyers) loaded them up", Iacocca , 79 and semi-retired in California, told Mustang Monthly in an interview published in the magazine's May issue. As head of the Ford brand during Mustang's gestation and birth, he kept the project under wraps so Ford executives, burned by the failure of the 1958-60 Edsel, couldn't say no to another radical idea. Then, when the idea was well along, he had to sell it to Chairman Henry Ford II.

Ford worked the original Mustang factory in Dearborn, Mich., for all it was worth, cranked up a second plant in San Jose, Calif., and the next year added a third in New Jersey to keep up with demand. Ford surpassed its goal of selling 417,000 the first 12 months.

But Mustang, which quickly got the obvious nickname "pony" and begat a genre of imitators called pony cars, was the only one meant for the masses. Designed as a low-price, high-style car that, in a radical departure for the times, would attract women and men equally, Mustang's appeal was immediate. It has created a legacy of Mustang anecdotes no doubt greater than the number of people who ever owned a Mustang.

Once the project came out of the closet, Ford Motor's three styling studios competed to design the Mustang.

The Oros design won, although there was a dicey moment when Chairman Ford bopped his head on the roof getting in and asked for more room. That was late in 1962, and Oros, Frey and their teams had a lot of work and little time. Iacocca wanted a showy start by unveiling the car at the 1964 World's Fair 18 months away.

Ford sold 1 million Mustangs in 24 months, a blazing start for a new model, then and now.

The car has had its close shaves. In the 1980s, it almost became a small, front-wheel drive, import-style, sporty car - a design Ford instead launched as the 1989 Probe coupe and discontinued after the '97 model.

"The '94 is when we changed back to what I thought the Mustang should look like", CEO Bill Ford says. He bought the first one.

The fifth generation begins with the 2005 Mustang, on sale in late summer or early fall. It uses wholly different hardware, adopts import-brand manufacturing techniques and looks more like the original Mustang than ever. And it has Bill Ford's strong support - no need for stealth and subterfuge.

"If you have a brand, and icon, like Mustang, and you treat it like just another vehicle, you're making an enormous mistake".