News on the internet is that the US version of the Fiat 500 will use the upgraded platform from the upcoming 2011 Fiat Panda and not the current European platform.
The European 500 will not receive the upgrade because the cost of switching the factory over to the new platform will be too expensive. The US 500 will get the upgrade because the 500 is starting fresh at a new factory.
This platform upgrade will give the US 500 an advantage over its European cousin.
The chassis on the current Fiat 500 was derived from the Fiat Panda (which dates back to 2003). It was upgraded and refined in 2007 for use in the 500 and has held up very well.
The new, redesigned 2011 Panda will use a further revised version of the current platform and boasts significant improvements in torsional rigidity, strengthened crash structures and improved noise, vibration and harshness (NVH) characteristics.
This has been achieved with the use of even more high strength steel compared to the current 500 platform, reinforcing the side rocker panels, the rear cross member and frame rails.
One significant feature of the new Panda platform is the wheelbase will be stretched to 2400mm, up 100mm from the current 2300mm. That leads to speculation that the 500 could also receive the longer wheelbase. However, the reports on the internet state that the US 500 will look identical to the European version.
I would say almost identical because the front bumper and the rear tailgate of the US 500 will be different to accommodate the North American license plate. That change alone cost Fiat $10 million .
With that cost in mind, it doesn't seem likely Fiat will make any changes to the wheelbase of the US 500.
The Fiat 500 Giardiniera
The Fiat 500 Giardiniera is a station wagon version of the normal 500 (à la Mini Clubman) and will use the extended Panda wheelbase. This model was tentatively announced last year as arriving possibly later this year and eventually coming to the US, however, lately there has been little talk from Fiat about this model. Due to the projected poor economic conditions this year, it appears the 500 Giardiniera intro will be delayed. It's better to introduce new models on an economic upswing which is expected to happen next year. We'll find out more in a few weeks when Fiat announces on April 21 its product plans for the next few years.
Summing up, if we can believe these reports (and they make sense), it sounds like great news! I'll keep an eye on this for you.