Common rail system for quiet running

Mixture preparation is performed by the newest generation of common railsystems. It features a high-pressure pump and an injection rail for eachcylinder bank. A high injection pressure of up to 2,000 bar (29,001 psi) -which equals the weight of a SUV within an area the size of a fingernail -permits an even finer atomization of the fuel, which provides better mixturepreparation and more efficient combustion.

The injectors in the common rail system employ the piezo effect, in whichan electric voltage is applied to a special ceramic, altering its crystalstructures. This results in a certain amount of expansion, which istransferred directly to the injectors.

Multiple injection events per cycle

With piezo injectors, the number of injection processes per cycle can bevaried and optimized almost at will. The Audi TDI development engineers haveopted for up to five injection processes for the 3.0 V6. In the lower speedrange, additional double pilot injection occurs in addition to the maininjection process; in the medium range there's single pilot injection. Simplepost injection occurs up to around 2,500 rpm and under partial load. Thisstrategy reduces emissions and ensures a smoother combustion process, whichprimarily benefits the engine's acoustic behavior. The 3.0 TDI produces aquiet, cultivated and harmonious sound.

The V6 TDI features a turbocharger with variable turbine geometry onboard. Its vanes are guided by an electric servo motor - this improvespropulsive power at low rpms. Two large intercoolers reduce the temperature ofthe compressed air in order to increase the overall efficiency.

The range: over 600 miles

The Audi Q7 3.0 TDI delivers powerful driving performance: the speedometerneedle takes just 8.4 seconds to go from zero to 60 mph. The V6 dieseldelivers 25 miles per gallon - providing a fuel range of more than 600 milesfrom a full tank that holds 26 gallons of fuel.

Total convenience for Audi customers

The AdBlue container is filled via the fuel tank flap, just like the fueltank. Its reservoir is divided into two containers - the active and thepassive tank. The biodegradable AdBlue solution is refilled at the workshop ateach service appointment, without requiring the customer to concern himself.Because of its low consumption, Audi ensures that the supply is sufficient tocover service intervals. The efficiency of the system is ensured throughoutthe lifecycle of the vehicle.

Thanks to its extremely low emissions, Audi can deploy its clean dieseldirect injection system worldwide, even in the U.S. states of California,Massachusetts, Maine, New York and Vermont, which have extremely stringentemission limits. Starting in 2010, the brand with the four rings will offerthe new technology in additional vehicle and performance classes.

Audi TDI - at the top for the past two decades

Audi is the pioneer in turbocharged diesel engines with direct injection -since 1989 the company has built and sold more than 4.5 million cars with TDIengines. From the very start, the initials TDI began to develop into a synonymfor superior propulsive power and a maximum efficiency; the technology hasadvanced to become a trendsetter for the entire automotive industry.

No other drive system has yet been able to beat the turbocharged dieseldirect injection engine when it comes to power combined with low consumption.When driven by consumers, consumption by TDI cars is up to 35 percent lowerthan comparable cars equipped with the gasoline engines typical in NorthAmerica.

The engine that Audi presented in late summer of 1989 at the Frankfurtmotor show: The five cylinder turbodiesel, installed in the Audi 100, featured2.5 liters of displacement for 120 hp and 195 lb/ft of torque. It was theworld's first diesel passenger car with direct injection and fully electronicengine management - the first TDI. With its brawny power, the five-cylinderengine, that went into regular production in what was then the fourthgeneration of new Audi 100s, set a new standard in the diesel sector. Sincethen, Audi has extended this technological advantage with continuous, newphases of development.

The TDI - the superior principle

The TDI engines from Audi are superior engines that feature commandingperformance and dynamic power. The 221 hp of the three-liter TDI that powersvarious Audi models, for example, provides about 80 hp of output per liter ofdisplacement - a level that just a few years ago was reserved for the sportscar segment. Thanks to their extremely low consumption levels and theirproliferation, especially in Europe, TDI engines have become the mostsuccessful efficiency technology in the world. When driven under realistic,mixed driving conditions, TDI cars generally also beat comparable models withhybrid drives.

TDI engines feature high propulsive power

The greatest strength of all Audi diesel engines is their tremendoustorque. Their propulsive power makes these diesel engines clearly superior toany comparable gasoline engine. This mighty power is also available atextremely low revs - just a little over idle speed - as a smooth butinsistently applied impulse that requires only the slightest pressure on theaccelerator.

In sharp contrast to many stressed, high revving gasoline engines, thepropulsive power is always available when it's needed - and this contributesto a highly composed, relaxed style of driving. In the style of the classicAmerican small block, the three-liter V6 produces 406 lb/ft of torque at thecrankshaft, which is available at just 1,750 rpm. The diesel engine produces137 lb/ft per liter of displacement - a level that far surpasses that of thegasoline engine.

TDI engines are efficient and economical

Diesel engines make more efficient use of the energy in their fuels thando gasoline engines.