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VWVortex.com Audi News Efficiency is the way into the future – Audi is introducing the current state-of-the-art for its fuel-saving technologies at the Paris Auto Show. The A4 TDI concept e technology concept has the agile handling characteristics typical of the A4, but requires just 3.99 liters of fuel per 100 kilometers (58.95 US mpg). This exemplary result was possible through the concentrated use of innovative efficiency modules.
Drivetrain and chassis The 2.0 TDI transfers its power to a six-speed manual transmission which is notable for its considerably reduced internal friction. It was specially customized to the high-torque TDI engine and has somewhat taller ratios for gears three through six. Most of the housing consists of ultra-light magnesium, which reduces weight by nearly 5 kilograms. A foam-packed skin serves as insulation, ensuring that the transmission oil heats up faster after the vehicle has been started. The drive shafts from the differential to the front wheels have also been redesigned. The transmission is coupled to a start-stop system that switches the engine off whenever the sedan comes to a standstill. The TDI is deactivated whenever the A4 TDI concept e comes to a standstill, the shift lever is in the neutral position, and the driver’s foot is off the clutch pedal. It starts up again as soon as the driver steps on the clutch – a specially developed starter handles this in around two tenths of a second, which is faster and smoother than a traditional component. While the driver puts the vehicle in gear, the TDI speeds up; as he takes his foot off the pedal, it drops down to idle speed. The start-stop system improves the exemplary fuel efficiency of the Audi A4 TDI concept e still further, meaning that 5 grams less of CO2 are produced per 100 kilometers – as measured on the dynamometer. And in actual terms this reduction may turn out even higher, as many trips to work are less than ten kilometers long and are frequently interrupted by traffic lights. Another important feature is that an electro-mechanical part replaced the electro-hydraulic power steering. This yielded a further reduction of 4 grams of CO2/km. It does not have to circulate any hydraulic fluid, nor absorb any energy while the vehicle is traveling in a straight line – its electric motor which provides power assistance only kicks in if the driver turns the wheel. The electrical brakes are another technology module that shows how meticulous the Audi engineers were in their approach to efficiency. Thanks to active brake control, residual brake torque is almost non-existent. It only arises if the small air gap that is necessary for a stiff feel to the pedal and immediate brake response results in a slightly unevenly shaped disk rubbing on the lining. Using electrical rear-axle brakes will achieve the same effect on the front axle: here, an enlarged air gap is also possible since the power brake system only has to carry out the lining displacement for one axle. Body and cockpit The A4 TDI concept e glides sleekly through the wind. A trunk lid with a restrained separating edge adds a further dimension to the already excellent aerodynamics. The partially closed grid in the single-frame grille and sporty suspension tuning with optimized ride height also contribute to the excellent drag coefficient of 0.25 (production model: 0.27). The underbody of the technology study painted in Daytona Grey is faired much more extensively than the production model; the rear lights feature LED technology, which uses much less power than regular bulbs. Newly designed, dip-polished cast aluminum wheels, of the size 7.5 J x 17 improve the flow of air around the wheels and wheel housings. The tires are designed for smooth running, but also provide sporty grip due to their 225/50 R17 wide format. The intricate technology package from Audi’s modular efficiency system also takes the most important external factor of all into account as far as possible: the person behind the wheel. Despite the prominence of high-end technology, the driver remains primarily responsible for how fuel-efficient his vehicle is. This is a fact that Audi takes very seriously in relation to its efficiency strategy. The driver will discover two major aids in the A4 TDI to help him drive economically. He can call up an efficiency program that shows up on the instrument panel display and which acts like an ecology trainer – pointing out open side windows or recommending rapid upshifting. And the navigation system will always offer an especially fuel-saving route as an alternative whenever the driver enters a destination.
The ‘e’ models from Audi The Audi ‘e’ models are especially progressive, combining maximum efficiency with excellent dynamics. The Audi A3 1.9 TDI e and the A3 1.9 TDI e Sportback both achieve standardized fuel efficiency figures of 4.5 liters per 100 km (52.27 US mpg) and a CO2 value of only 119 grams per km (191.51 g/mile). Both models have an output of 77 kW (105 hp) and a top speed of 194 km/h (120.55 mph). The new Audi A6 2.0 TDI e and its Avant equivalent are equipped with a 100 kW (136 hp) diesel. The sedan accelerates from 0 to 100 km/h (62.14 mph) in 10.3 seconds and has a top speed of 208 km/h (129.25 mph). Average fuel consumption for both models: only 5.3 l/100 km (44.38 US mpg). The A8 2.8 FSI e, with its 154 kW (210 hp) V6 on average consumes only 8.3 liters of fuel (28.34 US mpg), making it the most efficient gasoline engine in the luxury class. Audi plans to expand its ‘e’ model line in the near future and start putting further technologies from its modular efficiency assembly into production. By the year 2012, the brand with the four rings will once again have significantly reduced CO2 emissions while continuing to hone its sporty, elegant profile.
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