After gaining rights to the Firearrow/Firebomb design, Casaroll asked Ghia's U.S. representative (and eventual Dual-Motors VP) Paul Farago to further develop the Firebomb into a production-friendly vehicle.
The series-produced design utilized an even greater number of standard production MoPar fittings, the (road-legal) Firebomb two headlamp configuration, incorporated modest tail fins and was somewhat more slab-sided and square-edged in comparison to the Firearrow/Firebomb series.
[2] The "world's longest assembly line" involved transporting a Dodge frame and drivetrain to Italy, where the bodywork and interior was fabricated by the coachbuilders at Ghia; once the partially completed vehicles were back in the U.S. Dual-Motors handled the rest.
[3] With a retail price close to $7,500 ($84,051 in 2023 dollars [4]), the Dual-Ghia D-500 was about $200 more expensive than most American production luxury cars.
However, its price did not even come close to that of the ultra-luxurious 1956 Continental Mark II at $10,400, or the 1957 Cadillac Eldorado Brougham at $13,074, ($146,518 in 2023 dollars [4]).