Pumpe Deuse engines require an in-tank pump to provide fuel to the unit injectors. This OE pump made by Seimens/VDO is an ideal replacement for a failed PD pump. Adding a lift pump to VE engine cars takes work away from the rotary pump since fuel is provided under low pressure (5-8 PSI) to the injection pump whenever the ignition is on. This helps cold starting, makes the engine run smoother at low speeds, and provides more fuel at high load, especially helpful in modified cars. Installation requires a relay and power source. The pump will fit in the tank of A4 and A3 cars, although the A3 may require some work to make sure the fuel gauge reads accurately.