The revised software was first introduced in 2019 with the launch of the E-tron Sportback, but the update will now be rolled out to other models produced for the 2019 and 2020 model years.
Audi says the E-tron 55 quattro has gained a range extension of up to 12 miles (20km) - an increase of 5% - meaning the model is now capable of traveling 274 miles on a single charge.
The update enables the model’s battery to deliver higher net usable power, meaning the car can now benefit from 86kWh of its 95kWh battery when driving.
Audi also claims the update optimises the control of the electric motor at the front of the car, disconnecting it in situations where the car requires less power.
The cooling system – which, Audi says is the basis for fast charging, long battery life and consistent EV driving performance – has also been improved by lowering volume flow rates in the coolant circuit.
Some 34,000 E-tron 55 quattro models are eligible for the update, which can be installed for free at Audi service centres.