The catch was that Renault planned to market more imposing, status-symbol cars – Austral in 2022, Espace in 2023 and Rafale in 2024 – and 140 or 145 hp under their bonnets was not enough. In any event, Renault’s CEO Luca de Meo unambiguously and unapologetically stated that “We want to make the best hybrid powertrain in the world”, and tasked Gilles le Borgne (then Renault’s EVP Engineering) and Philippe Brunet (then SVP Powertrains) with delivering it using the first generation’s technology. They naturally sat down with the teams that had developed the E-TECH powertrain – who were already aware of this need and figuring out how to satisfy it.
We had already found the new ICE engine to replace the naturally-aspirated 1.6 engine of the 140 hp first-generation, and we knew what levers we could pull to further optimise power, driver comfort and efficiency. We were facing solidly established competitors and many new players and gave ourselves a year to optimise the electric motor’s performance, fine-tune the whole system, reduce consumption, shorten ignition time and smoothen gear shifts, among other things,
Developing the 1.3 TCe engine put us back in the technical race to build a high-efficiency petrol engine, but we had to take one step further,” he remembers. “At the time, in 2015-2016, we could see that regulation on the horizon would push diesel to the sidelines. We needed a new standard-setting petrol engine that would rank among the most energy-efficient on the market. Which is what we had done with the 1.5 dCi then 1.6 and 2.0 dCi diesel engines a few years prior.
At the time, all the petrol engines on the market carried surplus fuel to help keep their stochiometric mixture right at high speeds – in other words to keep the air-to-fuel ratio right in the combustion chamber, in order to avoid overheating. But we could sense that, sooner or later, this would be a problem from a regulatory standpoint. So we needed an engine that would keep the right stoichiometry however hard you pushed it. We were also certain that, to optimise efficiency, it needed the Miller cycle and a system to recirculate burnt gases with an EGR valve.”
Nissan had already fitted a petrol engine with an EGR valve – which cuts NOx emissions and improves efficiency by routing some of the exhaust gas back to the cylinders instead of releasing it. But Francis and his teams wanted to take one step further than their Japanese colleagues: “We were aiming for a 20% recirculation rate. So we had to shorten the circuit between the turbocharger and the air intake, and add a water-to-air intercooler (CAC), which wasn’t common on a petrol engine at the time.”
Speaking of cylinders, how many would this new ultra-efficient petrol engine have? Francis Boutonnet’s answer helps to understand the link with the E-TECH 200 hp engine: “We started developing this engine to use it ‘solo’, but we also reckoned it would work perfectly well in a hybrid powertrain like E-TECH. As long as we kept it compact enough to fit in all the engine compartments without making the powertrain heavier. So we went for a 3-cylinder architecture. As it happened, at constant capacity – in this case 1,200 cm3, it was actually more energy-efficient than a 4-cylinder architecture.”
We started equipping this ‘simple’ hybrid powertrain with the 400 V architecture from the plug-in hybrid powertrain we were using in Captur and Mégane. The first E-TECH generation only had a 230 V architecture. We put in a 2 kWh battery instead of the 1.2 kWh battery. That extra voltage increased the main electric motor’s power rating from 35 kW to 50 kW (48 hp to 68 hp).
Nicolas Fremau continues, “We had to strengthen the dog clutch gearbox so that it could handle the higher power and torque from the engine and main motor. While we were at it, we enabled the fifth gear (which was built into but not used in the first E-TECH version). To do that, we simply tweaked the gear ratios.”
Lastly, the new hybrid E-TECH 200 hp powertrain benefited from software upgrades and electronic enhancements that had already been used on the original 140 hp version. For example starting the engine with the HSG instead of a cylinder – which works better on cold mornings. Also noteworthily, they used the HSG – again – to adjust torque and thereby avoid turning off (and then having to turn back on) the ICE engine while shifting gears. “All that lowers consumption, and wipes out a further 2.7 grammes of CO2 per km!”, Nicolas Fremau adds.