Since 1998, Fiat's entry-level model in Europe had been the Polish-built Seicento, itself an updated version of the 1991 Cinquecento.
These models had only ever been sold with three doors, although Fiat had responded to the growing demand for five-door city cars in 2003 by launching the Panda, which replaced a three-door model of the same name which had slotted into Fiat's European range between the Cinquecento/Seicento and the larger Punto.
Around the time of the Panda's launch, Fiat set about developing a three-door city car to replace the Cinquecento.

Driven by the tremendous success of the Smart Fortwo, especially in Italy, Fiat began examining a variety of small car concepts "to regain its small-car crown," — developing an "intense interest at producing a Smart (Fortwo) competitor" — and concluding that "most customers want more than just the Smart's two seats."

The 2004 Fiat Trepiùno concept, from which the 500 derives, was introduced at the 74th Geneva Motorshow — designed at Centro Stile Fiat by Roberto Giolito in a style strongly reminiscent of the original Fiat 500¹⁹⁵⁷.
The name "Trepiùno" is a contraction of the Italian words "tre più uno", or "three plus one" in English; as the design accommodates three adults and one child — by reducing requirements ahead of the front passenger (with high-tech, space-saving, thin materials), sliding the front passenger forward, and positioning the third adult directly behind the passenger, allowing a fourth, smaller, occasional passenger to sit behind the driver.

The concept design was translated into the 2007 production model under the direction of Frank Stephenson.
According to Stephenson, aerodynamic concerns were paramount with the new 500, saying his team preferred the look without the spoiler as on the original Nuova 500.
 Nonetheless, the small rear spoiler at the top of the rear hatch provides a CD of .32 — where without the spoiler the drag coefficient would have been 0.40.

The 500 uses a widened variant of the Fiat Mini platform.
The 500 features Dante Giacosa's 1964 breakthrough front-wheel drive layout — which ultimately became an industry standard, the layout "adopted by virtually every other manufacturer in the world" for front-wheel drive automobiles.
Announced on May 5, 2006, photographs of the 500 were presented on March 20, 2007, officially debuting on July 4, 2007, with 250,000 people in attendance and with new models prominently displayed in 30 Italian cities.

The 500 uses Fiat's Multiair hydraulically actuated variable valve timing (VVT) engine technology, winner of the 2010 International Engine of the Year as well as Popular Science's Best of What's New.
Since 1998, Fiat's entry-level model in Europe had been the Polish-built Seicento, itself an updated version of the 1991 Cinquecento. These models had only ever been sold with three doors, although Fiat had responded to the growing demand for five-door city cars in 2003 by launching the Panda, which replaced a three-door model of the same name which had slotted into Fiat's European range between the Cinquecento/Seicento and the larger Punto. Around the time of the Panda's launch, Fiat set about developing a three-door city car to replace the Cinquecento.
Driven by the tremendous success of the Smart Fortwo, especially in Italy, Fiat began examining a variety of small car concepts "to regain its small-car crown," — developing an "intense interest at producing a Smart (Fortwo) competitor" — and concluding that "most customers want more than just the Smart's two seats."
The 2004 Fiat Trepiùno concept, from which the 500 derives, was introduced at the 74th Geneva Motorshow — designed at Centro Stile Fiat by Roberto Giolito in a style strongly reminiscent of the original Fiat 500¹⁹⁵⁷.
The name "Trepiùno" is a contraction of the Italian words "tre più uno", or "three plus one" in English; as the design accommodates three adults and one child — by reducing requirements ahead of the front passenger (with high-tech, space-saving, thin materials), sliding the front passenger forward, and positioning the third adult directly behind the passenger, allowing a fourth, smaller, occasional passenger to sit behind the driver.
The concept design was translated into the 2007 production model under the direction of Frank Stephenson. According to Stephenson, aerodynamic concerns were paramount with the new 500, saying his team preferred the look without the spoiler as on the original Nuova 500.  Nonetheless, the small rear spoiler at the top of the rear hatch provides a CD of .32 — where without the spoiler the drag coefficient would have been 0.40.
The 500 uses a widened variant of the Fiat Mini platform. The 500 features Dante Giacosa's 1964 breakthrough front-wheel drive layout — which ultimately became an industry standard, the layout "adopted by virtually every other manufacturer in the world" for front-wheel drive automobiles. Announced on May 5, 2006, photographs of the 500 were presented on March 20, 2007, officially debuting on July 4, 2007, with 250,000 people in attendance and with new models prominently displayed in 30 Italian cities.
The 500 uses Fiat's Multiair hydraulically actuated variable valve timing (VVT) engine technology, winner of the 2010 International Engine of the Year as well as Popular Science's Best of What's New.
Fiat 500 (2007)