Road Test: 2011 Audi A8 4.2 TDI quattro

Even bigger than before, the Audi A8 has grown in size with its new model. But thanks to it’s sleek body, it doesn’t really look that big, until you are standing next to it. It is easy to recognise the new A8 as a part of the Audi-family, because the design of the front and rear end resembles clearly smaller Audi-models. Maybe a bit too much. The new A8 doesn’t look bad this way either, but I would have like to see more individual appearance for this big car. Big and strong, but at the same time amazingly lightweight. With the use aluminum in the body structures Audi has once again set new standards for lightweight constructuin.

Audi A8’s low weight is also a key factor for achieving good driving dynamics. Audi introduced the technology of the Audi Space Frame (ASF) with the first A8 generation. Now Audi is again using it in a much more advanced form. Audi has substantially increased the strength of the body components in the new A8, thereby significantly reducing both material thickness and weight. With the use of the high-strength aluminum alone enabled a weight saving of 6.5 kilograms. Besides the low weight, the ASF body of the A8 has many other strengths. For example the static torsional stiffness has increased by 25 percent compared with the predecessor.

The new A8 made its debut on the market with a choice of two V8 engines, one gasoline and one diesel. All engines feature direct fuel injection, and consume up to 22 percent less fuel than their respective predecessors. The 4.2 FSI has the offers 372 horsepower and 445 Newton metres of torque. FSI engine accelerates the A8 from zero to 100 km/h in 5.7 seconds, with the electronically controlled top speed of 250 km/h. The average fuel consumption of this powerful V8 is still only 9.5 liters/100 km. A reduction by 1.4 liters or 13 percent compared with the predecessor, while the power increase is 22 hp. The CO2 emission rate is only 219 g/km.

This diesel V8 provides 350 horsepower and 800 Newton metres of torque which is available between 1750-2750 rpm. The TDI V8 accelerates even faster than the FSI. The sprint from rest to 100 km/h takes 5.5 seconds. Comparing to the previous version, TDI’s output has increased by 24 hp and 150 Nm, while the consumption has dropped by 1.8 liters/100 km, a full 19 percent. The new A8 with 4.2 TDI consumes 7.6 liters/100 km and the CO2 emissions are 199 g/km. The enhanced performance results from increased pressure of the common rail system, which now injects at 2000 bar. The reduction of the internal friction was another focus of development. The two turbochargers and the exhaust gas recirculation system have also been largely overhauled.

All engine versions have a new, electronically controlled 8-speed tiptronic transmission. It features two automatic operating modes; softer D and sportier S. There is also the tiptronic option, meaning that you can change gears by yourself. Although there isn’t really any need to do this, for couple of reasons. One is that the transmission works so great on automatic mode. The other reason is that it’s not easy to choose the right gear when you have eight choises to choose from.

The quattro all-wheel drive system is a another standard equipment on the A8. Its mechanical center differential manages the torque split. On normal conditions 60 percent of the torque goes to the rear axle and 40 percent to the front. If the wheels start to slip, the differential sends the large part of the torque to the axle with the better traction. Customers with a particularly sporty driving style may decide on the optional sport differential with its continuously variable distribution of the drive forces between the rear wheels. This sport differential is standard on the 4.2 TDI quattro. The sport differential’s controller is connected to the Audi drive select vehicle dynamics system. Audi drive select integrates the adaptive air suspension, the engine, the 8-speed tiptronic, the sport differential and the dynamic steering. With the MMI the driver can change the characteristics of these systems between comfort, auto and dynamic modes.