Audi Adds A4 and A4 Avant 2.0 TFSI Flex Fuel Models; Optimized for E85

15 September 2009

Audi has added new flexible-fuel versions to its A4 model series: The A4 and A4 Avant 2.0 TFSI flexible fuel can operate on up to E85 ethanol blends. The 2.0 TFSI flexible fuel engine is based on the 2.0 TFSI with Audi valvelift and start-stop system. Like that engine, it produces 320 N·m (236 lb-ft) of torque between 1,500 and 4,200 rpm and puts out 132 kW (180 hp).

The four-cylinder engine is optimized for operation on E85. E85 is currently available at nearly 300 gas stations in Germany, with Norway and Sweden having the densest network of E85 filling stations in Europe.

Audi takes advantage of the higher RON 110 octane rating of bioethanol to operate the engine at optimal efficiency. This reduces the roughly 40% greater consumption by volume that is a consequence of the lower energy content of ethanol and thus decreases the loss in range. The advantage of the Audi concept is that the engine can be operated on fuel with any concentration of up to 85% ethanol with no noticeable differences in drivability or performance.

The flexible fuel philosophy requires a series of technical modifications. One of the chemical properties of E85 is that it is highly corrosive to certain metals. The base engine had already been designed with these properties in mind, so no modifications to the fuel lines or seals were required.

A different material was required only for the valve seat rings due to the lower lubricating action of the ethanol. A sensor in the fuel line reports the ethanol concentration to the engine management system, which adjusts injection and ignition accordingly.

With E85, the four-cylinder unit achieves a fuel consumption of 9.0 liters per 100 km (26 US mpg) in the A4 Sedan and 9.2 liters per 100 km (25.57 US mpg) in the A4 Avant. With super unleaded gasoline it records figures of 6.4 liters per 100 km (36.75 US mpg) in the Sedan and 6.6 liters per 100 km (35.64 US mpg) in the Avant. Because taxes on ethanol are significantly lower than on fossil fuels, however, its use reduces operating costs.

The sedan accelerates from zero to highway speed in 7.9 seconds on its way to a top speed of 236 km/h (147 mph); for the Avant these figures are 8.1 seconds and 228 km/h (142 mph). Both models transfer power to the road via the front wheels and a six-speed manual transmission.