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NEW AUDI A4: THE BEST OF BOTH WORLDS

By ALISTAIR KENNEDY
8 March 2010

Audi has upped the ante in the ongoing battle between petrol/hybrid and diesel engines for the hearts and minds of the conscientious motoring public with the release of a new A4 diesel variant that combines outstanding fuel economy and excellent performance.

The new A4 TDI e sedan (the ‘e’ stands for economy) is a step up in size and power from the smaller A3 TDI e hatchback that made such a strong impression on us when it was launched in March 2008.

The main feature with both of these Audi ‘e’ cars is the use of the latest in turbo-diesel technology, with changes to the electronic ‘mapping’ of the engine able to reduce fuel consumption without any significant decline in performance.

The new A4 TDI e is powered by a 2.0-litre turbo-diesel engine that develops 100 kW, only marginally down on the 105 kW from the engine used in the standard 2.0 TDI. More importantly, peak torque is 320 Nm between 1750 and 2500 rpm while 0/100 km/h acceleration takes 9.5 seconds. Fuel consumption on a combined city/country cycle is just 4.8 litres per 100 kilometres.

According to Audi only about 50 per cent of fuel consumption is influenced by the engine and only a small percentage of this can be optimised. Other savings have been made by braking energy recovery which converts surplus kinetic energy to electrical energy during braking, enhanced aerodynamics including an underbody trim panel, partially enclosed radiator grille, and a 20 mm reduction in ride height.

Another piece of emerging technology that’s featured in the A4 TDI e is Audi’s Start-Stop facility. Designed to conserve fuel when a vehicle is stopped for any length of time it turns off the engine whenever the gear lever is in neutral and the clutch pedal is released. Then, when the clutch pedal is depressed, the engine re-starts. Importantly there are safeguards to ensure that the engine is not turned off before it has warmed up, if the interior temperature has not been reached, if the steering is turned sharply or if the car is stopped on a steep hill.

Audi claims that Start-Stop can reduce city cycle fuel usage by as much as 1.5 litres per 100 kilometres.

Technological improvements can only do so much in reducing fuel consumption and CO2 emissions. After that it comes down to the ability, and desire, of the driver to take advantage of the opportunities provided by the engineers.

Once again technology is there to help the A4 TDI e driver, this time with what Audi calls its Driver Efficiency Program. This uses an on-board computer to not only provide immediate and average fuel consumption but also to suggest ways of reducing it including recommending gear changes, showing the effect on consumption of having the air conditioning or rear window heating turned on. It will even warn when windows are left open and the air conditioning is on.

To test Audi’s claims we drove the A4 TDI e from the centre of Adelaide to Broken Hill. The first surprise came in the drive through the Adelaide city and suburbs, where congestion and traffic lights combined to give Start-Stop a rigorous workout. By the time we had moved into the rural section of the route fuel consumption was showing just 3.9 litres per 100 kilometres, seeming to back up Audi’s claimed 1.5 L/100 km saving through Start-Stop.

From there we moved up to a comfortable cruising speed of 110 km/h which we were able to maintain most of the way to the Silver City. Despite pushing the car relatively hard at times the combined fuel usage had only risen to 5.4 L/100 km by the end of our test. While the terrain on the route between Adelaide and Broken Hill isn’t the most demanding with few hills and long straight stretches of good quality bitumen roads this is still an impressively low rate of fuel consumption. Indeed other cars, driven more conservatively, were able to record sub-5.0 numbers.

Importantly the trip was made in complete comfort with most of the luxury features expected from an Audi vehicle.

Another surprise is the price. At $49,900 (excluding on-road costs) the TDI e is the cheapest model in the A4 range. It is only offered with six-speed manual transmission.

Audi does have more ‘e’ models in the pipeline although no dates have been released as yet. These will include an A6 2.0 TDI e with diesel consumption of 5.3 L/100 km and an A8 2.8 FSI e with petrol consumption of 8.3 L/100 km. Other technologies such as Start-Stop and energy regeneration will be added progressively across the Audi range.


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