The Fiat Siena 1.4 TetraFuel, which offers a choice of four fuel types, has just gone on sale across Brazil, and represents the latest pioneering model from Fiat Automòveis, the autonomous South American arm of Fiat Auto.

The Siena 1.4 TetraFuel thus becomes the first production vehicle in the world to be able to use four different fuel types, mixed, which enable the Fiat 'World Car' family 4-door saloon to be fuelled with a either choice of gasoline, gasohol (blend of gasoline mixed with 22 percent alcohol), pure alcohol and CNG (Compressed Natural Gas) or combinations of them.

Delivery of the Siena's innovative TetraFuel system is controlled by a specially-designed chip fitted within the car's Electronic Control Unit (ECU), which has been developed by the Fiat Group's Magnetti Marelli division. This chip smoothly controls the optimum use of the petrol and gas mixtures while the car is in use, without the driver having to place any input into the operation. Unlike 'dual fuel' systems there are no cockpit controls used to make manual adjustments to the process.

The Siena 1.4 TetraFuel thus chooses automatically the fuel option for each required driving situation scenario to reach the optimal compromise between performance and fuel economy. Fuel economy is the system's embedded principle function, but it swiftly reacts to a situation where another overriding priority may occur, such as the requirement for an increase in torque from an uphill situation. Maximum power available from the 1396cc, 4-cylinder engine is 80CV at 5,500 rpm (using gasoline only), 81CV at 5,500 rpm (alcohol) or 68CV at 5,500 rpm (GNV). Maximum torque is 12.2 Kgm at 2,500 rpm (for either gasoline or gasohol), 12.4 Kgm at 2,250 rpm (alcohol) or 10.4 Kgm at 2,500 rpm (GNV).

The Magneti Marelli TetraFuel system, which is based on a fully integrated low-pressure approach and not on an adaptation, as are current retrofit systems, decreases significantly pollutant emissions and in particular the GHG-emission (Green House Gas, that is CO2). The engine and cylinder head have both been significantly revised with new components and materials being used throughout. A special new set of injectors have been developed which can be switched out of use as load requirements dictate. New valves (two per cylinder) and camshafts are complemented by a revision to the geometry of the cylinder head's chambers and passages, while the engine features Magnetti Marelli's multipoint electronic ignition.
 

The base of the rear trunk area of the Siena has been strengthened to accommodate the two new GNV cylinders, each of which can each hold 6.5 m2 of gas at 200 bar pressure. The rear springs have been modified and a bigger diameter stabiliser bar has been incorporated to keep it at the same ride height (and offering the same handling characteristics) as the Siena 1.4 FlexFuel. Likewise the rear brakes have also been beefed up. Inside the cabin has a new set of instrument gauges indicate to the driver the level of GNV available, a low GNV indicator warning light, indication if damage is occurring to the system, external temperature and a trip computer.

If the volume of gas in the GNV tanks drops below 4 percent then the system will automatically switch away from gas (the driver has been previously advised of the low level through the dashboard visible warning indicators) and likewise a similar scenario occurs if pressure drops below 10 bar, actions that preserve the integrity of the system and prevent any possible irregular flow of gases. Passive safety of the TetraFuel system has also been carefully addressed. The GNV tanks have been fitted in a protective environment and the car has been crash- and fire- tested rigorously. The two tanks have been designed to interrupt feeding of the GNV if any breach in either cylinders occur, and similarly any overpressure will result in GNV being released into the atmosphere.

The TetraFuel system was thus entirely developed in Brazil, by Fiat Automòveis along with Magnetti Marelli and Fiat Powertrain Technologies, and follows in a long line of technical innovations to arrive on the market ever since Fiat introduced alcohol fuelling for their cars in 1979. The most recent innovation from Fiat Automòveis was the SFS (Software FlexFuel Sensor) technology that allows Fiat models to use ethanol alcohol, gasoline or any blend of the two fuels. This 'dual fuel' technology has become hugely popular in recent years in Brazil as alcohol fuel has seen a resurgent in popularity partially due to rapidly rising oil prices. This year the majority of cars sold in Brazil will incorporate 'dual fuel' technology.

Fiat Automòveis see the Siena 1.4 FlexFuel as having strong export potential as alongside its reduced dependence on oil, it also offers inherently reduced pollutant levels. The major car-using regions of the world are seeing strong environmental pressure to reduce overall vehicle pollutant emission levels, particularly so in North America, China and Europe. Toyota recently announced that it proposes to introduce ethanol powered cars into the USA while the Financial Times this week reported that Fiat CEO Sergio Marchionne (along with his counterpart at VW/Audi) had raised the subject of financial incentives for biofuel cars when they recently met and dined informally with the EU Industry Commissioner, Günther Verheugen.

The Fiat Siena 1.4 TetraFuel will be introduced to the Brazilian market offering a high level of standard equipment including front electric windows. Options include additional airbags, air conditioning, metallic paint and equipment packs: 'Kit 30 Anos', 'Kit Vivace', 'Kit Hitech' and Kit Iluminacao' either a one-year unlimited mileage warrantee or a four-year warrantee with mileage limits. Pricing is R$41,900 to retail customers and R$31,750 for taxis (São Paulo market).