The Mercedes EQXX has demonstrated its outstanding efficiency by managing to cover more than 1000 km in open traffic from Sindelfingen in Germany to Cassis on the Côte d’Azur via the Gotthard tunnel, the Swiss Alps and Northern Italy.
On Google maps there are 1,017 km between Sindelfingen, Germany and Cassis, a port town near Marseille on the Côte d’Azur, via the Gotthard tunnel, the Swiss Alps and northern Italy. Driven on the motorway at up to 140 km/h and close to the maximum legal speed limits almost everywhere, the Mercedes EQXX arrived at its destination with about 15% of battery power remaining, corresponding to a remaining range of 140 km.
The fuel consumption of 8.7 kWh/100 km is an absolute record. There is no electric car that consumes so little, and the conditions under which this consumption was achieved were not the most favourable. The temperature along the route ranged from 3 degrees at the start in Germany to 18 degrees at the finish.
The first part of the route ran from Sindelfingen to the north-eastern border of Switzerland on the A81 motorway where the Mercedes EQXX travelled at speeds of up to 140 km/h. At high speeds, aerodynamics is crucial and the sensational Cx of only 0.17 contributed greatly to the very low energy consumption. The EQXX has a small frontal area of only 2.12 sq m, the rear track is 50 mm narrower than the front, the active rear diffuser that protrudes out at 60 km/h gives better airflow to the rear of the car and the Bridgestone tyres developed especially for the EQXX with the 185/65 R 20 97T size have a very low rolling resistance, are 20% lighter and deform less while driving thanks to a more tensioned belt section.
Then, when climbing the mountains to the entrance of the Gotthard tunnel, the lower weight of the car mattered a lot. Although it has a 100 kWh battery, the Mercedes EQXX weighs only 1755 kg. The battery has a capacity almost equal to the Mercedes EQS but is 50% smaller and weighs 30% less. With dimensions of 200 x 126 x 11 cm the battery weighs only 495 kg and can fit in a compact car. The battery has an energy density of 400 Wh/l and operates at a high voltage of over 900V.
The electric propulsion system was developed in cooperation with experts from the Mercedes-AMG Petronas F1 team.
Then, on the descent out of the Gotthard tunnel, the Mercedes EQXX demonstrated the efficiency of the braking energy recovery system so that mechanical brakes were rarely used. The EQXX uses aluminium brake discs for the first time, which are considerably lighter than steel discs.
In the sunny Italy, the 117 solar cells on the roof proved their efficiency and provide energy for the 12V battery that powers auxiliary consumers such as the navigation system.
The propulsion system consisting of the 180 kW electric motor, transmission and power electronics was developed together with F1 specialists at HPP. The propulsion system has an incredible efficiency of 95%, which means that 95% of the battery energy reaches the wheels.
Due to the fact that the electric motor generates little heat loss due to its outstanding efficiency, passive cooling is sufficient. The cooling plate in the unterbody uses the air current for cooling and this increases the range by 20 km. Although in the ascent to the Gotthard tunnel, the engine was runing at full load mostly of the time, the air shutters remain closed.
Mercedes EQXX managed to cover the 1008 km route in just 11 hours and 32 minutes and the on-board computer shows a remaining range of 140 km. The average speed was 87.4 km/h and the maximum speed on the highway was 140 km/h.