Since the dawn of the automobile, drivers have been forced to choose between fuel economy and performance. Even during the fuel crises in the 1970s and early 1980s, you could buy high-performance cars, but they always came at a significant fuel economy penalty. Today's TDI® clean diesel Audi models let you enjoy the efficiency benefits of diesel technology, without sacrificing the performance that Audi drivers expect.1
The inherent, efficient power of diesel, married to the performance boost of turbocharging, means Audi TDI® clean diesel engines provide greater torque, lower fuel consumption and lower CO2 emissions compared to gasoline engines of similar size.2 Power and efficiency are what allowed the Audi R10 TDI® to win its maiden race at the 2006 24 Hours of Le Mans. Since then, Audi TDI® technology has won six Le Mans titles.
TDI® clean diesel engines feature direct injection technology which means that the engine is directly injecting fuel, in precise quantities, to the combustion chambers at exactly the right moment. The addition of turbocharging simply forces more air — at a higher rate of speed — into the combustion chamber.
Turbocharging is doubly efficient because the turbine it uses to force that air into the system is powered by exhaust gases created by combustion, rather than drawing power from an external ancillary drive belt, the way a supercharger operates.
More energy + high compression = more power
Every drop of diesel fuel contains about 15 percent more energy than the same drop of gasoline. It means that you can drive further on every tank of ultra-low-sulfur diesel fuel than a gallon of gasoline.2
But what makes diesel perform is compression. During the compression stroke, traditional gasoline engines without direct injection compress a mixture of fuel and air in the combustion chamber. Diesel engines only compress air, at a much higher pressure than a gasoline engine can. Then, at the moment of highest compression, the system injects a precise amount of diesel fuel into the combustion chamber. The hot, compressed air ignites the fuel, without the need of a spark plug ignition system.
Horsepower vs. torque
Engines don't produce horsepower, engines produce torque — the twisting force transferred through the drivetrain to the wheels.
Horsepower is the amount of torque applied over distance and time. Torque is what gets your car moving. The higher the torque and the lower the rpm, the more powerful the car feels when you merge onto the highway or leave a stoplight.3
Compare two Audi engines: The Audi A8 L features a 3.0-liter, TFSI® V6 engine. It delivers 333 hp at 5,500 rpm and 325-lb.ft. of torque at 2,900 rpm.
Now take a look at the A8 L powered by a 3.0-liter TDI® clean diesel V6: It provides lower horsepower of 240 hp at 3,500 rpm. But the twisting force of the engine it builds is not only much higher at 406-lb.ft., it's available at much lower rpm, just 1,750, meaning that when you need that power most, it's available.
Turbocharging, direct injection, greater power density and high compression working in concert: It's the recipe that helps make TDI® clean diesel-powered Audi models not only powerful, but simultaneously more efficient. The time is right for you to experience it for yourself.
1 See www.fueleconomy.gov for EPA estimates and emisions information. Your mileage and emissions will vary and depend on several factors including your driving habits and vehicle condition.
2 2014 Audi A8 L TDI® clean diesel: 36 hwy/24 city/28 combined mpg EPA estimates. Range of 666 combined miles based on 28 mpg combined EPA estimates and a 23.8 gallon fuel tank. 2014 Audi A8 L 3.0T: 28 hwy/18 city/21 combined mpg EPA estimates. Range of 491 combined miles based on 21 mpg combined EPA estimates and a 23.4 gallon gas tank. Your mileage will vary and depends on several factors including your driving habits and vehicle condition. CO2 emissions comparison based on EPA data. See www.fueleconomy.gov for details. Your mileage and emissions will vary and depend on several factors including your driving habits and vehicle condition.
3 Always obey speed and traffic laws.