Despite having some advanced design features such as flush rivetted all-metal construction and a retractable undercarriage, the final generation of biplane fighters was being supplanted by monoplanes and the Gregor FDB-1 was obsolete before it flew.

In 1938, Georgian expatriate designer Mikheil Grigorashvili (anglicized as Michael Gregor) joined with Canadian Car and Foundry, which at that time was Canada's leading manufacturer of railroad rolling stock.

[1] The cockpit was enclosed with a rearward sliding canopy and the engine was faired in with a NACA cowling reminiscent of the Seversky monoplane fighters that Gregor had worked on.

The center section of the top wing curved down to meet the fuselage, in a gull-wing configuration like earlier Polish and Soviet fighters such as the Polikarpov I-153.

A wood wind tunnel model was sent to Hawker Aircraft in England for testing early in 1938, and construction of the prototype began in Thunder Bay shortly thereafter, with it completed in December 1938, "amid an atmosphere of war jitters, well salted with tales of German spies visiting the factory in disguise.

"[3] When rolled out, the FDB-1 c/n 201 was registered CF-BMB, with the letters and ten horizontal rudder stripes in white over a dark gloss metallic gray.

[5] Top speed was anticipated to reach 300 mph (480 km/h) with a 750 hp (560 kW) Pratt & Whitney R-1535-SB4-G, however installation of military equipment would have more than eliminated any gains.

At the time of testing Gregor was redesigning it to accept the 1,200 hp (890 kW) Pratt & Whitney R-1830 Twin Wasp which he hoped would raise the top speed.

As can be expected from a biplane without the weight of 8 machine guns, or armour to slow it down, the FDB-1 demonstrated amazing maneuverability and despite a speed advantage, the RCAF's Hawker Hurricane Mk.I monoplanes were unable to turn with it below 15,000 ft (4,600 m).

Can-Car entered it in the January 1940 New York-to-Miami air race in a final effort to generate interest but shortly after takeoff oil pressure was lost, forced the FDB-1 to land, disqualifying it.