E-Tech 4x4 300 hp: the challenges of an expertly crafted E-Tech super hybrid

Renault Rafale E-Tech 200 hp was introduced to the press at the Paris Air Show on 18 June 2023. Unveiling the brand’s new flagship, Luca de Meo, CEO of Renault Group, said:

“Rafale is reconnecting Renault with a long-held dream, a dream in which the brand demonstrates its ability to scale new heights, and even target the highest end of the market.” Luca de Meo

This enigmatic statement became a reality in November 2024 with the press test drive of the “advanced performance” version of Rafale: the E-Tech 4x4 300 hp.

Renault Rafale has a clear brief: to pursue Luca de Meo's clearly stated ambition to target the top end of the market with a demonstration of technological excellence. To achieve this, Luca de Meo talked about a psychological figure of 300 horsepower. This is the output of the future powertrain developed specifically for the exclusive, advanced performance version of Renault Rafale.

For the project engineers, it was clear that the advanced performance version of Rafale had to be powered by E-Tech, and it was their role to take the system to new heights of technical and technological excellence! Nicolas Fremau, Alexandre Herrero, Corentin Kerouredan, Octavie Okamba-Diogo and Romain Saulnier – all experts in their respective fields – pooled their skills to address this inspiring challenge.

Challenge No. 1: manage the energy flow and 4x4 transmission

The powertrain engineers at the Technocentre never do things by halves, and in this case, they already had an excellent base for the future 300 hp 'super hybrid’: the E-Tech 200 hp. Nicolas Fremau, an expert in the hybrid technology implemented by the E-Tech powertrain, took part in drafting the initial outline of the project: “The 1.2-litre 3-cylinder petrol engine of the E-Tech 200 hp  powertrain delivers peak efficiency of up to 43%. To generate an additional 100 hp, our only solution is to fit a bigger turbocharger and to add a second electric motor to the powertrain. To power this motor and obtain a range that is sufficient for everyday use, we need to install a more powerful battery and turn the powertrain into a plug-in hybrid.”

The new-generation CMF-CD platform implemented for Renault Rafale is sufficiently modular  to accommodate a rear-mounted electric motor and a 22 kWh rechargeable battery under the floor. This configuration is also the best in terms of weight distribution. For the 'super hybrid' project, the rear-mounted electric motor has two main advantages: first, the layout under the bonnet is the same as for the E-Tech 200 hp, and second, the motor is connected with the rear wheels, enabling 4-wheel drive operation. This feature is highly appreciated by customers in the high-end SUV segment. And so the technical characteristics were finalised. The future Rafale 300 hp would be a 4x4 plug-in hybrid.

As well as selecting the powertrain components, the engineers had to make sure that they formed a functional whole. This was the area of expertise of our function/calibration experts “We faced two main difficulties in tuning the engine,” begins Alexandre Herrero “We had to manage the constraints relating to front and rear axle torque, and also to ensure efficient 4x4 transmission with no mechanical link between the front and rear motors” Alexandre Herrero continues.

As explained in Episode 3 on the Energy Management at the heart of the E-Tech system, the vehicle relies on ECUs for the smart management functions. “For the software configuration of the engine ECU, we developed a highly complex energy management strategy based on speed, torque and battery charge level. Each parameter had to deliver a smooth, dynamic experience, regardless of driving conditions” he explains.

Alexandre Herrero and Corentin Kerouredan made full use of the incredible versatility offered by the software-controlled engine and transmission. In terms of traction, all four drive wheels are ready at all times. Torque distribution can vary instantly from 100% at the front (front-wheel drive) to 100% at the rear (rear-wheel drive), depending on the settings selected by the driver, the driving style and driving conditions. As a general rule, front-wheel drive is preferred up to 70 km/h, and rear-wheel drive at higher speeds.

In terms of powertrain operation, the engine or one of the motors can be disconnected at any time (hybrid or all-electric mode) to continuously optimise fuel consumption. “The software functions continuously assess the requirements in terms of power and energy, based on a multitude of variables including battery charge level, driving profile (speed and acceleration), road conditions (gradient, speed), as well as the weight of the vehicle (maximum towing capacity of four tonnes). The magic of the E-Tech system is to constantly achieve the best compromise between the traction of a 4x4 and the maximum efficiency of all the energy sources. In this way, the vehicle makes maximum use of the combustion engine in the operational zone around the point of maximum efficiency. And all this is entirely transparent for the customer! We managed to combine excellent traction with a high level of efficiency” says Corentin Kerouredan with enthusiasm.

Challenge No. 2: create a new plug-in hybrid powertrain

Transforming a 'full hybrid' into a 'plug-in hybrid’ with a rechargeable battery involves more than just adding' a plug. Not only is the battery of the E-Tech 4x4 300 hp powertrain ten times more powerful than on the E-Tech 200 hp (22 kWh compared with 2 kWh), its chemistry is also fundamentally different. The composition and architecture of a battery depend on several criteria, including range, power requirements and frequency of charging and discharging.

“For Rafale to continuously deliver 300 horsepower at the wheel, we developed a 22 kWh battery based on NMC (nickel-manganese-cobalt) technology, with the emphasis on power. Working with our colleagues from powertrain development, we had to find compromises. It wasn’t solely about performance at the wheel. The car had to deliver in terms of handling, range and reliability” explains Octavie Okamba-Diogo, Battery Function Coordinator.

For optimum battery performance, the ideal temperature is 25°C. Given the size of the battery and the power requirements, the thermal management of the cells was a major challenge. For a smooth, fast and efficient temperature increase, the project team developed an aluminium heating mat. Using a power resistor, this mat provides +2° of heat /minute. “Without this innovation, the increase in battery temperature would be ten times slower, with a negative impact on performance” continues Octavie Okamba-Diogo.

Challenge No. 3: manage complex powertrain and software functions

In view of the many function settings available with Renault Rafale E-Tech 4x4 300 hp in the Atelier Alpine finish (four engines/motors, 4-wheel drive, 4-wheel steering, regenerative braking and smart suspension), the main task of Romain Saulnier and the other engineers was to simplify vehicle usage, allowing the driver to focus on the driving experience. Drivers can customise their driving experience with three menus: Multi-Sense, E-Save and the new Agility Control.

Drivers can customise driving sensations with the Multi-Sense function and its four modes: Eco, Comfort, Sport and Snow. The variations in steering effort, engine response and chassis agility deliver different driving experiences, from dynamic driving in Sport mode to increased traction in low-grip conditions with Snow mode.

The EV Mode button on the centre armrest provides access to three driving modes: Hybrid (default), Electric (all-electric up to 160 hp and a top speed of 135 km/h) and E-Save (battery charge maintained above 25% using the combustion engine as a generator).

Available only on the Atelier Alpine finish, the Dynamic Chassis menu on the multimedia system lets the driver optimise settings for the Advanced 4Control function, the damping profile and the ESP, based on three options: Comfort (ideal for everyday journeys, particularly in the city), Dynamic (for a compromise between agility and a damping) and Sport (with a focus on handling and driving pleasure).

“With these three easy-to-select drive modes, all optimised by Alpine Cars, drivers can be confident that they have the ideal set-up for driving Rafale E-Tech 4x4 300 hp Atelier Alpine” says Romain Saulnier, Performance Coordinator.

Renault Rafale E-Tech 4x4 300 hp delivers the best of both worlds: electric and plug-in hybrid. For day-to-day driving, electric mode is activated on demand, in the same way as an all-electric car with a range of up to 105 kilometres (WLTP EV cycle). This capacity encourages regular plug-in charging. On long journeys, fuel consumption is on a par with the best, at(0.5 l/100 km with a full battery and 5.8 l/100 km with an empty battery for the Esprit Alpine finish (WLTP figures), allowing the vehicle to cover up to 1,000 km on a single tank of fuel. In Sport mode, handling is particularly efficient, with acceleration from 80 to 120 kph in 4 seconds - the best in the SUV market, including the premium segment.

Under the bonnet of Renault Rafale, the E-Tech 4x4 300 hp powertrain thereby satisfied all requirements, pushing the boundaries of excellence still further for E-Tech in terms of performance, sporting qualities and efficiency.

“With the E-Tech 4x4 300 hp powertrain, we aimed for the Moon, but went to Mars” concludes Nicolas Fremau.