The engine can be started only with an original Audi key and only when the clutch pedal is depressed (on vehicles with a manual gearbox).
Vehicles with a petrol engine:
Manual gearbox: Press the clutch pedal all the way down and move the gear lever into neutral.
Automatic gearbox: Press the brake pedal and move the selector lever to position P or N WARNING!.
Turn the ignition key to position -2- and release it again. Do not press the accelerator while waiting.
Vehicles with a diesel engine:
Manual gearbox: Press the clutch pedal all the way down and move the gear lever into neutral.
Automatic gearbox: Press the brake pedal and move the selector lever to position P or N WARNING!.
Turn the key to position -1-. The indicator lamp 
will light up to indicate that the glow plugs are preheating.
will light up to indicate that the glow plugs are preheating.Turn the ignition key to position -2- and release it again. Do not press the accelerator while waiting.
When starting from cold the engine may be a little noisy for the first few seconds until oil pressure has built up in the hydraulic tappets. This is quite normal and no cause for concern.
If the engine fails to start straight-away, switch off the starter after about 10 seconds and try again after about half a minute.
Glow plug system* (diesel engines)
The preheating time depends on the outside temperature and the temperature of the coolant. When the engine is warm, or at outside temperatures above +8°C, the glow plug indicator lamp will come on for approximately one second. This means that the engine can be started immediately.
will come on for approximately one second. This means that the engine can be started immediately.Caution!
Avoid high engine speeds, full throttle and extreme load conditions until the engine has reached its normal operating temperature, otherwise this can damage the engine.
For the sake of the environment
Do not warm up the engine by running it with the car stationary. You should drive off immediately whenever possible. This will help avoid unnecessary exhaust emissions.