Audi chooses high technology but cautious design evolution for new A4

  • 13-Jul-2015 03:34 EDT
Audi06=15 A4 2.0 TFSI quattro 1.jpg

The fifth-generation Audi A4's road presence is about evolution and aero efficiency with a best Cd of 0.23. Compared to the previous generation, all panels have been changed and the grille redesigned.

Audi’s just revealed 2016MY A4 is a classic example of automotive evolutionary design. Its aesthetics are not quite ripe for a game of “spot the difference” between the new fifth and previous fourth generation of this hugely successful model line, but they are close to it, even though every panel has been changed.

What this car is about, is evolution, technology, and systems’ development; development of practically every aspect of its being (including new engine technology), without risking the sort of image step-change that Mercedes-Benz took in 2014 with the rival C-Class, a decision that has paid huge dividends in terms of sales and brand appreciation.

The new A4’s reveal (sedan and Avant) in Germany ahead of its public unveiling at September’s Frankfurt Motor Show was not accompanied by any official public comment by Audi’s main Board members, who presumably are allowing the car to “speak” for itself.

In a sense it does so: check out the interior space and it has increased; try the headlights and (optional) matrix LEDs, developed in conjunction with Hella, will illuminate; interrogate the MMI and natural language voice control will respond; and the car gets Audi’s virtual cockpit technology that it is rolling out to embrace its wider model range.

The A4’s suspension has a redesigned five-link system front and rear to provide improved levels of ride comfort and sharper handling; one of its transmission options incorporates freewheeling; engine choice includes units providing exceptionally low fuel consumption and CO2 figures; and the A4 sedan is highly aerodynamically efficient, with a Cd of only 0.23.

Perhaps Audi reckons it has a classic design signature (such as the 911, Beetle, Mini) that can just be massaged every few years as technology is updated and efficiency improved. But it is what is inside the wrapper, rather than the wrapper itself, that really distinguishes the A4’s advance.

While the A4, using the MLB (modular longitudinal) EVO platform, gets a plethora of advanced electronic infotainment and connected systems, the fundamentals of improving a vehicle remain vital, with weight reduction still a salient issue; the 120-kg (265-lb) improvement against the fourth-generation car is significant.

Intelligent materials

The 1.4 TFSI gasoline base sedan has a 1320-kg (2910-lb) mass empty and without driver. The car’s body is 15 kg (33 lb) lighter than its predecessor thanks to “geometrical lightweight construction and an intelligent combination of materials”—mainly aluminum and high-strength steels.

The module crossmember under the dashboard is now of extruded and sheet aluminum, the front crossmember an extruded profile. The mounts for the front MacPherson struts are highly integrated aluminum castings for an 8-kg (18-lb) savings. The construction is said to allow a very stiff connection between the upper ends of the struts and the car body for optimal driving dynamics.

Hot-stamped components form the high-strength, crash-proof backbone of the passenger compartment. They strengthen the transition from the front of the car to the interior, the frontal area of the roof frame, the B-pillars, the doorsills, and parts of the floor—and constitute 17% of the body structure. Interior weight watching includes lightweight seats.

The A4 sedan’s length is 4726 mm, 25 mm (1 in) longer than the previous model. Width expands 16 mm (0.6 in) to 1842 mm (72.5 in). Height remains 1427 mm (56.2 in). Wheelbase is stretched 12 mm (0.5 in) to 2820 mm (111.0 in). The Avant is 1 mm (0.04 in) shorter and 7 mm (0.3 in) taller than the sedan but all other dimensions are the same.

Audi claims up to a 21% fuel consumption improvement for its latest engine range. Initially it spans from four-cylinder 1.4-L gasoline to six-cylinder 3.0-L diesels; power output spreads from 110 to 200 kW (148 to 268 hp).

The A4 2.0-L TDI (diesel) ultra (efficiency) sedan delivers a very frugal fuel consumption of 3.7 L/100 km, with CO2 emissions of 95 g/km. But gasoline technology developments are also bringing impressive results.

Ultra solution

Audi’s gasoline 2.0-L TFSI ultra model produces 140 kW (188 hp) and maximum torque of 320 N·m (236 lb·ft) from 1450 to 4200 rpm. Performance figures include 0-100 km/h (0-62 mph) in 7.3 s and a top speed of 240 km/h (149 mph) for the sedan with an S tronic transmission. NEDC (New European Driving Cycle) fuel consumption is a very good 4.8 L/100 km and CO2 emissions are 109 g/km.

Audi reveals that new technology is contributing to this efficiency. The 2.0 TFSI (see http://articles.sae.org/14140/) employs a new combustion method with shorter compression and longer expansion phases, and raised compression is designed especially for partial load, the intake valves closing much earlier than usual. Together with increased pressure in the intake manifold, this reduces throttling losses.

Because of the shortened compression phase, the compression ratio is upped from 9.6:1 to a heady 11.7:1. So in the compression phase, the engine has only to compress as much gas as a 1.4 TFSI. In the expansion phase, it gains from the high compression ratio, the resulting higher level of pressure during combustion further increasing the engine’s efficiency.

For the 2.0 TFSI air/fuel mixture to swirl sufficiently despite the short intake time, the combustion chambers, piston recesses, intake ducts, and turbocharging are specially adapted. Under higher loads, the Audi valvelift system opens the intake valves later, resulting in a higher charge, which ensures good power and torque delivery. Injection pressure has been increased to 250 bar (3.6 ksi).

On the transmission front, the Multitronic CVT system has been dropped and choices now embrace a redeveloped six-speed manual, seven-speed dual-clutch S tronic, and eight-speed Tiptronic conventional automatic.

Playing the Cd game

While weight reduction and advanced powertrains are at the epicenter of Audi’s efficiency, aerodynamics have taken a very significant step with the new car, as Audi shows Mercedes-Benz what it, too, can do in that discipline. The sedan’s 0.23 Cd is complemented by the Avant’s 0.26.

Audi explains how some of it is accomplished by attention to fine detail.

The outer lines of the air inlets integrate additional openings, guiding some of the air stream over the wheel well, where it flows past wheels which have also been aerodynamically optimized.

The Avant gets a roof edge spoiler with a positive downward slant, and narrow trim on both sides of the back window aid airflow.

The underside of the engine compartment of both A4 versions is sealed from the road, and broad trim under the passenger cell and the luggage compartments protects the metal. The wishbones on the rear axle are enclosed and small spoilers guide the airflow at various areas of the car.

The A4 TDI ultra gets a controllable cool-air inlet. A frame installed behind the radiator grille houses two blinds that can be activated independently. They are closed as the car starts so that air resistance stays as low as possible; when air is needed to cool the engine, first the lower and then the upper blind opens.

The accent on aerodynamic efficiency has also been aimed at providing the A4 with a notably quiet cabin, particularly at high cruising speeds.

Electronic upgrade

However, it is the level of cabin and electronic driver support technology that increasingly establishes a new car’s status.

For the A4 it includes, depending on version and trim level, the Audi virtual cockpit with 12.3-in LCD screen with high resolution graphics; predictive efficiency assistant; traffic jam assist; rear cross-traffic assist; collision avoidance assist; and turn assist. There is an Audi smartphone interface, Audi Drive Select, and a second-generation modular infotainment platform with a 7-in color MMI (Multi Media Interface) monitor.

The infotainment system includes MMI Navigation Plus, MMI Touch, and Virtual Cockpit developed with Harman and Bosch. The modular infotainment system processor, called MIB II, is a Nvidia quadcore Tegra 30 chip.

An optional Audi tablet, available as a rear-seat entertainment device that’s portable, employs a Google Android operating system and Nvidia Tegra 40 processor.

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