Two experimental concept cars, each built: around the new European Ford Fiesta, will be exhibited by Ford Motor Company's Ghia Operations of Turin, Italy, at the New York Auto Expo, April 2-10,

Making its United States debut will be the Corrida -- a sporty fastback 2+2 coupe with gull-wing doors, recessed concealed headlamps and a bottom-hinged tailgate.

The four-in-one Prima -- the result of a collaboration-between Ford's Design Center in Dearborn, Mich, , and the company's Ghia studios -- also will be on display.

It was shown publicly for the first time in California in 1976. A multi-purpose vehicle, the Prima can, within minutes, be converted into four different body styles by the addition of easily detachable roof sections.

Based on. the sporty European. Fiesta "S" model, the Corrida is a design project with emphasis on. performance, according to Filippo Sapino, Ghia. managing director.

The car's top-hinged gull-wing doors fold in the middle to provide unrestricted access to the interior, even when the Corrida is parked within a confined space. In addition, the doors' hinge mechanisms are designed to give additional  strength to the car's roof structure. Opening and closing of the doors is assisted by pneumatic pistons, Corrida's third roar door is hinged, at the bottom and can be locked in. the "open" position, to increase both the length and capacity of the load space. When the tailgate is in the "open" position, a special, cover makes the load space completely waterproof

Outside, the Corrida, features a hold two-tone black-and-red paint treatment and sporty forged-aluminium wheels. Inside, are contoured seats for the driver and front passenger. The rear seat, which can be folded down as part of the luggage compartment, will accomodate two additional, passengers. However, it in intended primarily for use on short trips.

In it is basic form, the Prima is a. two-a seat pickup truck. By adding three different removable tops, it is converted quickly into a two-seat sports coupe, a 2+2 three-door fastback, or a four-seat station wagon.

"While the Prima in essentially an idea car, " said Mr. Sapino, "it incorporates technical and design features that make it a. highly 'practical approach to meeting the current market demands for an economical, utilitarian vehicle."

Both the Prima and Corrida have 90-inch wheelbases, transverse-mounted engines and front-wheel drive, which eliminates the drive-shaft tunnel and makes possible, in the case of the Prima, a wide range of body styles within the same basic vehicle.

Prima's different steel tops are clamped into place with simple latches similar to those that fasten a soft convertible top to a windshield. The fastback top includes a hatchback or third door in. the rear. The rear of the station wagon top lifts, while the bottom can be lowered to provide easy loading and unloading.

Recessed, rectangular headlights highlight the front of the Prima. Three horizontal chrome moldings extending around the front fender corners to the wheel cutaways conceal slots that direct cooling air to the engine compartment. Similar chrome strips accentuate the rear of the vehicle.

The Prima's interior features tan contoured leather accented bucket seats. The rear seat pulls down to form part of the floor in the pickup, and to provide additional carrying capacity in the fastback and wagon versions.

"It should be emphasized that both the Corrida and the Prima are concept models and are not intended for production," Mr. Sapino said. "However, these cars enable us to    public reaction to one or two of the many ideas which are being developed by Ghia designers as possible transportation of the future.