Tri-Flex Car


Brazilian Car Can Use Natural Gas, Alcohol, or Gasoline

Here is an idea, how about building a car that runs on natural gas, or 100% alcohol, or 100% gasoline, or any combination of alcohol and gasoline. Well, its not a concept car but a reality in Brazil where you can buy such a car right off the showroom floor that runs on three different types of fuel. Fiat Motors in Brazil makes such a car and they call it a tri-flex.

The car has two cylinders for natural gas storage in the trunk that holds 11 cubic meters of natural gas. It has a regular gas tank as well that can hold alcohol, gasoline, or any combination of the two fuels. The on-board computer knows which fuel is available and it chooses natural gas as its first choice if it is available. If the natural gas runs out, it switches automatically to alcohol or gasoline depending which one is in the tank. The switch is made seamlessly and the only indication that the fuel source has been switched is a red light on the dashboard that indicates that alcohol is now being used instead of natural gas. When the natural gas cylinders are refilled, the motor starts burning natural gas once again.

Refilling the car with natural gas is very quick and convenient. The filling apparatus looks very similar to an air hose used to put air in the tires. There is a valve under the hood, which you open up to attach the hose and within a few minutes the tanks are recharged to a set pressure. The tanks must be refilled to a prescribed pressure and you can't partially fill the tanks, they must be completely refilled. The filling station where we went was running low on natural gas so they did not have enough pressure in their tanks to completely refill our tanks, so the cylinders in the car were only filled to 80% capacity. There is a separate fuel gage on the dashboard indicating how full the cylinders are in the car. The car's computer can tell you the mileage being achieved by the car and how many more kilometers worth of gas remain in the cylinders.

Comparison of Fuel Prices in Brazil
Fuel Price MileageCost per Km/Mile
Gasoline (100%) R$ 2.52 per/liter 15-16 kilometers per/liter R$ 0.16 per/kilometer
  US$ 5.63 per/gallon35-37 miles/gallon US$ 0.153 per/mile
Alcohol (100%) R$ 1.25 per/liter 11 kilometer/liter R$ 0.11 per/kilometer
  US$ 2.79 per/gallon26 miles/gallon US$ 0.108 per/mile
Natural GasR$ 1.52 per/m3 18 kilometers/m3 R$ 0.08 per/kilometer
  US$ 0.89 per/m3 11 miles/m3 US$ 0.079 per/mile

The above chart lists the three types of fuel the car can use and the important number of course is the cost per kilometer/mile driven. When you compare those numbers, you can see the tremendous advantage of natural gas. The cost of using 100% alcohol is about 68% as expensive as using gasoline and the cost of using natural gas is 50% as expensive as using gasoline. With those sorts of economics at play, everyone is considering purchasing one of these tri-flex vehicles or converting their existing vehicle to natural gas. The natural gas option straight from the factory cost and additional R$6-7,000 or US$ 3.500-4,100, but conversion kits are available in Brazil for about R$ 4,000 or US$ 2,350. The one drawback of the conversion kit is that the driver must manually push a button on the dashboard telling the engine to switch from one fuel to the other while the factory option does it automatically.

The conversion kit pays for itself once the vehicle travels 30,000 miles. The natural gas option from the factory pays for itself once the vehicle travels about 50,000 miles. Those figures are based on today's prices, once more companies start marketing the natural gas option, the cost of this option will come down. All of these calculations are based on the exchange rate of 1.7 reals per dollar.

The use of natural gas for vehicles in Brazil is quite new. It is only in recent years, with the completion of a natural gas pipeline from Bolivia, that an abundant supply of natural has become available in central Brazil. The price of natural gas spiked in 2008, but generally it is the cheapest fuel source for vehicles in Brazil. This is another good example of just committed Brazilians are to the development of alternative fuels.