At the recently ended 2006 New York International Auto Show, Nissan, and its Infiniti luxury division, unveiled cars of extreme significance: the midsize 2007 Nissan Altima and the entry-luxury 2007 Infiniti G35 sedan. Both cars represented breakthrough design and were styling standouts when introduced in their current versions; the new ones are evolutionary, at least in appearance. Is the once-bold Nissan, basking in its newfound success, now playing it safe?

And, in a sense, who could blame Nissan for playing it safe and not tampering with success? Indeed, the Nissan turnaround story has the drama and so-far happy ending of a Broadway production. Nissan was down and nearly out in the late 1990s when Carlos Ghosn, now chief executive of both Renault and Nissan, stepped in with a revival plan. Keys to Ghosn's plan were setting precise sales and financial targets while demanding head-turning designs.

His plan was a phenomenal success. In the U.S., Nissan's sales soared 58 percent from 1999 to 2005, market share rose from 4 percent to 6.3 percent, and operating profit margin jumped from 1 percent to a best-in-industry 9 percent. In late April, Nissan reported its sixth consecutive year of higher profits. Two stars in the production were the Nissan Altima and Infiniti G35.

In 2001, Nissan was selling a mere 150,000 Altimas in the largest-volume car segment in the U.S. (about 4 million total sales annually). The dramatically redesigned 2002 Altima set itself apart from the Honda Accord and Toyota Camry by targeting the 20 percent of the segment that Nissan found was bored with existing offerings and wanted style and performance. The Altima was advertised as "the cure for the common sedan." As Ghosn pointed out in New York, the Altima cured a lot of Nissan's ills by stimulating sales and profits as well as drawing attention to the brand.

Named North American Car of the Year at the 2002 Detroit Auto Show, the Altima became Nissan's top-selling vehicle; 2005 sales surpassed 250,000 vehicles, making it the fourth best-selling car in the U.S., with some of the youngest buyers in the segment, Nissan claims.

"By every measure, the Altima is a resounding success, a power brand in our rejuvenated product lineup," said Ghosn.

At Infiniti, the eye-catching G35 is the most successful Infiniti in history and is the luxury marque's volume leader, representing one of every three Infinitis sold. As Ghosn further pointed out in New York, the G35 laid the foundation for Infiniti's recent success — four straight years of record profitable sales and a 55-percent increase in sales volume since 2002.

Now comes Act II, and the New York show saw the curtain rise on its opening.

With the Nissan and Infiniti vehicle lines completely overhauled, the next re-do is starting. Again, the Altima for Nissan and the G35 for Infiniti will be among the headliners. The 2007 Altima was unveiled at the New York show as a concept and goes on sale this fall with a hybrid version — Nissan's first hybrid in the U.S. — arriving in about a year. The G35 sedan hits showrooms in November.

When he introduced the Altima at the New York show, Ghosn said Nissan was "taking a very good car up to the next level." He described it as an evolution of the car's "iconic design" (iconic is definitely a stretch) but "a revolution in the interior and under the skin."

The new Altima's shape is leaner, more defined. The biggest change is inside, where it needed it most. On the concept at least, vastly higher grades of materials are used, fit and finish is improved, and the overall cabin, which is just as big as the current one, is taken up a notch. The new Altima is the first vehicle to use the new "D" platform developed cooperatively by Nissan and Renault. The new architecture is said to be more rigid and, paired with a redesigned suspension, promises even more spirited driving dynamics.

Similarly, the new G35 is more refined, much needed effort has been placed on interior craftsmanship, and technology has been cranked up a notch. The first of the second-generation G35 models — the sedan — was unveiled in New York and goes on sale in November. A coupe follows in 2007; a concept version was revealed at the Detroit show earlier this year.

In his speech to the International Motor Press Association at the show, Ghosn talked about Nissan's need to "go farther in embracing design and create better visual passion." He said, "Design has been a driver of our success, and we are pushing innovation farther than ever."

But one wonders if Nissan truly is pushing the envelope this second time around as it did in the first instance. Time will tell as Nissan and Infiniti kick off a second product blitz, which will include the Nissan GT-R and a new Z.

And one wonders if Ghosn, hailed as Nissan's savior, is another Lee Iacocca, who thrives on turnarounds more than everyday operations. If that's the case, we've got a couple of car companies here in Detroit that could use a turnaround specialist.