Ford chose to continue its fourth generation Taurus, critical to the company's fleet sales (to large corporations, small businesses, rental car firms, utility companies, and government agencies) and overlap that production with the Five Hundred, emphasizing its optional all-wheel drive and continuously variable transmission, extensive safety features, large interior volume and high H-point seating, the latter marketed as Command View seating.

The Five Hundred's 203hp engine and conservative styling became points of criticism, and sales fell markedly short of company projections — requiring substantive discounts by its second model year.

As part of the 1999 acquisition of Volvo Cars and its addition to Premier Automotive Group, Ford Motor Company expanded on its vehicle safety technology capabilities and began development of a 4th generation (D186) Taurus replacement.

[14][15] In 2000, Ford presented the Prodigy concept, a 72 MPG diesel-electric hybrid designed as part of the Partnership for a New Generation of Vehicles.

[3] Ford vice president Phil Martens noted that at a time when the industry was trying to design car-based crossovers, the Five Hundred was the first crossover-based car.

[19] Front seats sit on a hydroformed cross-car steel beam between the B-pillars (directly below an identical beam above the B-pillars), complemented by reinforced roof crossmember[18][20] — marketed by Ford as SPACE architecture (Side Protection and Cabin Enhancement), an adaptation of Volvo's Side Impact Protection System (SIPS), channeling impact forces around the passenger compartment.

[18] The Five Hundred/Mercury Montego was powered by a single engine, shared with the Ford Taurus: a 203 hp 3.0L Duratec V6, paired with a 6-speed Aisin automatic transmission (for front-wheel drive versions) or a ZF CVT (for AWD), the latter a first for a US domestic automaker.

Both SEL and Limited trims manufactured after September 4, 2006 received two-row side curtain airbags, marketed as the Safety Canopy.

[18] Using new powertrain electronics, the Five Hundred employed a CAN bus system with a Black Oak controller and PowerPC machine language and floating-point calculations for improved execution times.

[26] For the 2007 North American International Auto Show, Ford introduced a mid-cycle 2008 update of the Five Hundred and Montego; the new sedans had front and rear fascia styling, new interiors, and new powertrains with a 263 hp 3.5L V6 and a new 6-speed automatic transmission.

Although the Taurus had been out of retail markets since 2006 (the Sable, since 2005), Mullaly cited the larger brand familiarity of the Taurus/Sable nameplates as the reason for the renaming of the two D3 sedans.

[11] Overall: The Five Hundred was well received for its SUV-like packaging with a raised overall height, elevated seating and large interior volume — as well as its extensive safety features and available CVT transmission and all-wheel drive.

[34][35][36][37] Styling: The Five Hundred's design team had aimed for guilt-free, unpretentious luxury,[40][41] and assessments ranged from handsome and elegant[42] to overly conservative.