Five experimental special purpose vehicles for limited urban transportation were demonstrated in Warren, Mich., as part of the General Motors Progress of Power presentation.

Two of the small sized ears were gasoline powered, one electric powered and a fourth was driven by a hybrid gasoline-electric system. The fifth was a mockup body and chassis with a hybrid system power plant. Four of the vehicles were built for two passengers only and the fifth was a two plus two configuration-two adults in the front and two children in the back seat facing the rear.

Harry F. Barr, vice president in charge of GM Engineering Staff, described the cars as" engineering studies with actual vehicles of many shapes and sizes and various forms of power."

Design and development of the four operational vehicles was directed by GM Engineering Staff in collaboration with GM Styling Staff and Delco-Remy Division. The fifth, XP-883, was initiated by GM Styling Staff.

512 HYBRID GASOLINE-ELECTRIC

This vehicle is a first generation concept for General Motors Engineering Staff's 512 series. Originally, it was built with an electric power plant and is now being used to evaluate, a hybrid concept. It has a 50-inch wheelbase, 66-inch length, 58-inch height and 52-inch width. Curb weight is 1,250 pounds.

Construction is a combination of aluminum panels and tubular steel frame. The hybrid's power system consists of a 12 cubic inch gasoline engine coupled with a series d-c electric motor through an electromagnetic clutch. With the clutch energized, the gasoline engine and electric motor both operate at the same speed and arc coupled to the differential and axle through reduction gears. Electrical energy is supplied by a 72-volt power battery pack with an additional 12-volt accessory battery.

In the hybrid mode, the peak horsepower is 13.8, top speed is 35 miles per hour, and the car accelerates from 0 to 30 miles per hour in 16 seconds. Its range at 30 miles per hour in the electric mode is 5.2 miles. It is approximately 150 miles in the hybrid mode with three gallons of gasoline.

512 ELECTRIC

The fresh, attractive design that can be achieved with a two-passenger urban vehicle is dramatized in this electric version of the 512 series. The exterior body is fiberglass with a steel chassis floorpan and rollbar. The car can be driven in fair weather with the canopy front raised and back light retracted, giving it a unique convertible appearance. Or it can be driven as a roadster with canopy removed.

Wheelbase is 52 inches, overall length is 86.3 inches and width 56 inches. Curb weight is 1,250 pounds with an 84-volt power battery pack. The power plant is a d-c series Delco-Remy motor with solid state controls. It utilizes special Delco-Remy lightweight lead-acid batteries that represent a forward technological step and contribute to the vehicle's range and performance.

A built-in battery charger simultaneously recharges both the main power plant and accessory battery. Complete recharge from a 115-volt household outlet requires 7 hours. The car's range at 25 miles an hour is 58 miles. At 30 miles an hour, the range is 47 miles. As more advanced batteries become available, these range mileages will increase. Acceleration from 0 to 30 is 12 sec­onds.

512 GASOLINE VEHICLE

Of the three-car experimental 512 series, the gasoline engine version emphasizes the sporty appearance. It is a roadster with integral plastic construction, 52-inch wheelbase, 86.3-inch overall length, 55-inch width and 51.9-inch height. It weighs 950 pounds.

The power source is a 19.6 cubic inch two-cylinder 12-horsepower aluminum engine with 11-1 compression ratio. It is adaptable to future emission controls, and is equipped with an experimental catalytic converter and air injection system.

A distinguishing feature of the power train is an automatic transmission operating on the variable ratio V-belt principle with a centrifugal clutch.

Top speed is 45 miles per hour and the car will accelerate from 0 to 30 miles per hour in 18 seconds. With a four-gallon fuel tank, its range is approximately 280 miles.

511 COMMUTER

The 511 commuter vehicle with its three-wheel suspension is a departure from conventional automotive practice. A special purpose car, it is designed to transport two people from suburbs to downtown offices at freeway speeds.

The three-wheel design-one in front, two in rear-provides excellent stability and maneuverability. It reduces weight, simplifies steering and allows for an uncomplicated "backbone" type of frame and makes possible a streamline shape. The low center of gravity, only 13 ½ inches off the ground, offers exceptional lateral stability and cornering ability.

Two steering systems have been tested in the 511, one a simple handle bar with 2-1 ratio and the other a more conventional steering wheel system with 9-1 ratio.

The rear-mounted engine is a four-cylinder 66 cubic inch Opel capable of 67 horsepower at 6,000 r.p.m. The transmission is a three-speed automatic torque converter type unit. The commuter can accelerate from 0 to 60 m.p.h, in 16 seconds and has an 80 m.p.h. top speed. In city driving it averages 30 to 35 miles per gallon.

Other 511 specifications: Overall length 149.0 inches, wheelbase 86 inches, rear tread 54 inches, overall width 63 inches, height 40 inches, ground clearance 4.5 inches, weight 1,300 pounds.

XP-883 CAR

A special purpose commuter vehicle, the XP-883 is designed to accommodate a hybrid gasoline-electric power plant with front wheel drive. At its present stage of development, the car is in mock up-condition.

The XP-883 has a two-door fiberglass body and will, seat four occupants-the driver and one adult passenger in front and two children facing the rear in a back seat. The backs of the passenger seats fold down to provide a cargo space 84 inches in length. Access to the rear seat area is provided by an upswinging door at the rear of the car.

XP-883 has a 68-inch wheelbase with an overall length of 122.2 inches. It is 57.3 inches wide and 46.3 inches high. Both front and rear tread are 49 inches; front overhang is 27.5 inches and rear overhang 26.7.

The XP-883 operates in either an all-electric or hybrid mode. In either it is accelerated from 0 to 10 miles per hour by the electric motor. At that speed in the hybrid mode, the gasoline engine starts and provides the power function for steady speed operation as well as power to recharge the car's batteries. Both power plants are automatically combined for acceleration.