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19/01/2011 1312

General Motors - TPC

WARREN, Mich. – An experimental  two-passenger car that achieves 95 mpg on the Environmental Protection Agency’s highway cycle has been developed by General Motors Advanced Product and Manufacturing Engineering Staff, according to Robert J. Eaton, GM vice president in charge of the staff.

“This small but spacious car – named the Two Passenger Commuter (TPC) – was built to measure the practical limit of fuel economy against the design of the other  cars throughout the world.”  Mr. Eaton said. “To make the TPC competitive on a world-wide basis,  some minor government emission and safety standards peculiar to the United States were excluded.”

Mr. Easton emphasized that while the TPC is an experimental vehicle it is still very practical. “We have learned many things in designing this vehicle that could be incorporated on the future production models.”

The TPC achieved 68 mpg and 95 mpg on the EPA city and highway driving cycles, respectively while meeting the EPA emission requirements. This outstanding fuel economy was achieved through using lighter – but non-exotic  -- materials; a low aerodynamic drag force; a high level of powertrain efficiency, and low rolling resistant chassis elements. With just a 4-gallon fuel tank, the TPC’s driving range would be 270 miles in typical commuter operation and 380 miles in normal highway driving.

Weighing just 1,070 lbs and having 80.2” wheelbase, the TPC is constructed primarily of light-weight steel, but the entire front end of the TPC, as well as the doors and rear fenders, are made of aluminum. Presently, GM’s lowest weight production vehicle – the Chevrolet Chevette – weighs 2200 lbs.

The 128.4” length of the car and the 46.3” height  belie the interior spaciousness: 32.4” shoulder room; 37.2” head room, and 42.5” of leg room.

Throughout the design process, the TPC was tested extensively in the GM Aerodynamics Laboratory (wind tunnel). It boasts a very slippery surface – .31 aerodynamic drag coefficient. The minimal frontal area contributes significantly to the very low aerodynamic “drag force” of 4.9 sq. ft. (The “drag force” is a product of the drag coefficient and the frontal area.)

Other contributing factors to the low aerodynamic drag are: flush glass; rear view mirrors mounted inside the passenger compartment;  tires flush with the wheelhouse and wheel flush with the tires;  tapered front fenders; a sloped hood; rear roof extension; ventilation air flow underneath the roof extension; an air dam that is integral with the front end panel, and large radii on front panels and windshield pillars.

These aerodynamic factors, plus the unique .8 liter three-cylinder engine and a five-speed manual transmission, provide acceleration from 0-30 in 5.3 seconds and from 30-60 in less than 13 seconds.

The 120 lb. engine features a lightweight block, head, ram-tuned intake manifold and valve cover assembly – all made of aluminum. Ram tuning – an effective and highly efficient method of delivering ambient air under natural pressure to each cylinder – is coupled with sequential port fuel injection to receive maximum power output from the low-friction engine.

Other fuel-saving and innovative features of the TPC include: zero-drag drum brakes on all four-wheels; low rolling resistance tires; and transverse-mounted composite plastic beams in the front and rear suspension that combine the functions of spring, control arm and roll bar.

source: General Motors. Please mention when using this text.

Engine & performance:

Type: 3-cylinder

Capacity: 800 cc

Power: 40 hp


Length: 3261 mm

Width: 1430 mm

Height: 1176 mm

Wheelbase: 2037 mm

Weight: 485 kg



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