Renault CTO Gilles Le Borgne: 'We can keep mobility affordable'

Millions of cars on the road today in Europe bear Gilles Le Borgne's imprint. Before being named head of engineering at Renault Group in 2020, he held a similar post at PSA Group, now part of Stellantis, where he worked for three decades. Le Borgne has taken on even more responsibility at Renault since February, when he was named chief technology officer. Le Borgne, a two-time Automotive News Europe Eurostar winner, recently spoke with ANE Associate Publisher and Editor Luca Ciferri and News Editor Peter Sigal about his most pressing challenge: How to improve the efficiency of electric cars so they are more affordable and sustainable.

Efficiency, as measured in kilowatt hours per 100 km, is becoming a critical topic for electric cars. Where is Renault now?

We are in the vicinity of 13 kWh/100 km for the Megane E-Tech (compact), which has a WLTP range of up to 470 km. We know that drivers can reach 450 or even 480 km in normal temperature conditions. This is where we stand right now but we are working on all aspects that influence efficiency.

What are some of those areas?

Regarding the powertrain, when you consider the motor, inverter and the power electronics, we are at a little less than 86 percent global efficiency [meaning the percent of electricity that powers the wheels]. The motor plus power electronics, about 90 percent. We are working on the next generation of EVs, which will arrive around 2027 and will include motors developed with Valeo. We are sticking with an EESM [externally excited synchronous machine], double winding motor with rotor and not with permanent magnets. We hope to increase the efficiency of the motor plus power electronics to 93 percent, which is quite good compared with a permanent magnet motor.

What about charging?

We are moving to gallium nitride (GaN) technology for the charging to gain something around 2 or 3 percent efficiency compared to current silicon-based technology. When you start with a conventional DC/DC with a silicon IGBT [insulated gate bipolar transistor power module, or switch], you are somewhere around 93 percent efficiency, and with GaN we hope to be around 95 to 96 percent. This will appear with the generation of EVs launched around 2027.

And on the battery side?

We will move to 800 volt for that generation, lowering the resistance of the cells. Another important point around the battery is preconditioning the temperature before you charge. Thanks to Google’s route planner, when you plan a recharge, the car knows you are going to stop and in case of cold conditions, it warms the battery to be more efficient at the start of the charging. But you need to use the route planner. It’s very, very efficient: When you stop at -5 degrees, with a charge of 15 percent, it will take 46 minutes without preconditioning for the Megane to reach 80 percent charge. With preconditioning, it’s 24 minutes, so almost twice as fast. Experienced users know to extensively use preconditioning because it’s not only about fast charging, but also about cost. If you stop at a Ionity station, for example, when you have preconditioning you can lower the cost from 84 euros to about 20 euros (at -5 degrees) because it takes you 105 minutes charging with average power that is quite low without preheating, and with it you can go as fast as 24 minutes. You pay based on minutes, not kilowatts.

Where else can gains be found?

We are working on aerodynamics, on friction, on the envelope of the car. On one level, the car is a machine to push air, so you need to reduce the drag coefficient and rolling resistance from the tires. Today we are in the range of 5 to 5.5 kilos per ton of rolling resistance for the tire. I'm fighting with the styling guys on the S [frontal surface area] because they want very large tracks and very big wheels, as usual. We will find a compromise on the S, but on the Cx (drag coefficient) we are working hard to reach 0.25, a figure that is quite good. We could say that apples to apples, we could save something around 2.5 kWh of energy for a given car for the same autonomy if we make all these efficiency gains. If you stick to the current cost of 120 euros per kWh (of battery), you can make the calculation yourself in terms of cost. Or you could increase the range by 30 to 50 km.

So you are aiming for 10.5 kwh per 100 km by 2027?

Let's say 11, because that's a technical target -- and then comes the styling guys!

How does the massive amount of energy needed for heating and battery management affect performance? 

We think we we are more than OK compared with our competitors regarding derating [operating at less than maximum capacity to preserve system life, ensure safety and other factors]. If you over-rate [range] then you have to lower performance to give you a chance to cool down the system. It’s difficult to tell your customers that they will not get all the performance that they thought they were getting. But one thing we have noticed -- because all our cars are connected -- is that even though EVs have really good acceleration, people drive very gently on a daily basis. We think we can benefit from this, although we need more data from the field, but it may allow some derating and reducing the size of the cooling system.

How much energy is used to cool or heat the battery in extreme heat or extreme cold?

The most demanding situation to cool the system is when you are at charging stations because there is no cooling wind when you are not moving.

Looking at real-world range, in city driving you are very close to WLTP homologation but what do you lose in highway-only driving?

Under normal conditions with intermediate temperatures, at 125 kph your highway range is about 30 percent lower than the homologated figure.

Cold starts can be scary for EV drivers because the computer will tell you that you have very little range.

We are working to correct that. Today, we are on the pessimistic side, because as you drive the battery warms up and the range goes up. But when you start it can be worrying. Unfortunately, our algorithm, which wants to be really safe, will indicate 240 to 260 km of range on a theoretical WLTP range of 450 km. But what we see on the data we are collecting now, we plan to adjust the gauging for autonomy to never indicate less than 300 km if you are fully charged [on the Megane], even in low temperatures.

Will there be a big improvement with battery cells, or has it already happened? 

Today we are at about 600 watt-hours per liter of energy density. We are planning to introduce 700 W-h/l, especially for Alpine, and we are working on 750 W-h/l. Solid-state batteries can reach 1,000 W-h/l, but we will have to wait and see. If you remember, we started at 250 or 300 W-h/l with the Zoe in 2021, so we have more than doubled the value. 

You have said that it is crazy to put more than 100 kWh of battery capacity in a car. But some new full-electric pickups in the U.S. will have more than 200 kWh.

My view is that we need to learn how our customers are using their cars; we need to improve range and efficiency as much as we can -- and then we need to decrease battery capacity as soon as the charging network enlarges. By doing that we can keep mobility affordable for all of our customers. Today, if you go up to 120 or 150 kWh, at the end of the day you need to bear the cost.

What is the right range for a small car like the Renault Clio? 

We have a lot of experience with this type of car because we have made several versions of the Zoe; the one we are selling today has 395 km WLTP range. From what we know, if it’s mainly an urban or commuting car, you have no problems with 400 km; of course depending on usage you could offer 300 km.

What about a larger car, compact and above?

Here, you need to shoot for something like 600 km, but again it will highly depend on the charging network. We are aiming for 600 km for the Renault Scenic [compact SUV], or more or less 400 km highway range.

When will customers start buying EVs on efficiency rather than just range?

That is a very difficult question. Today we are stuck at 15 percent EV sales in France, and a little bit less overall in Europe. But my feeling today is that it's not a normal market because of incentives. Automakers are investing billions in what is really not yet a natural market. In the next 24 months we will have a complete lineup of EVs. But we need to have people to buy them without incentives. 

Renault has very efficient full hybrids like the Austral, and you're strong in electric. Are plug-in hybrids in your court?

They are, actually. Today, we have the Megane and Captur PHEVs, and we will introduce a PHEV soon with 280 hp. I'm a big fan of plug-in hybrids. The big fault of all the automakers was to use them as a tax incentive collector. I drove the plug-in hybrid Captur for two years and I was able to see fuel consumption of 3.5 liters per 100 km because I could charge on a daily basis. 

What are your views on e-fuels?

Renault will be working with Aramco on e-fuels, and we have done testing with e-fuels coming from pilot plants. We know the advantages; we have done our life-cycle analysis, but there are two issues around e-fuels. For one, I urge the European Commission to use a “cradle-to-grave” carbon emissions analysis and not “tank to wheel.” Tank to wheel makes sense if we are talking about internal combustion engines, because 80 to 85 percent of the CO2 comes from the usage of the car. Nevertheless, it’s not relevant if you are talking about EVs, where it’s always zero tank to wheel. If you have a big battery, then you need to amortize it also in terms of CO2. This is another reason not to go to silly levels of energy onboard -- if you have a 150 kWh battery, you have a big amount of CO2 to reimburse from Day 1.

What is the other issue?

You need to process e-fuels using clean energy like solar or wind -- I would call it decarbonized energy. You can recapture CO2 or use biomass to get CO2, then you combine with green hydrogen and you have a drop-in fuel. 

Isn’t it much more efficient to make BEVs, because it’s inefficient to use a lot of energy to create e-fuels?

Yes, but it’s only inefficient if you have a problem with getting enough green energy. Energy companies like Total, Shell or Aramco are operating in very sunny, windy countries where they can invest in e-fuels.

What about using e-fuels for new cars?

We have a chance to revisit EU emissions rules at the close of 2026. It could also be a solution for Dacia, because the brand will have to move gradually to clean energy. 

Is there anything on the engine side that needs extra maintenance, or do they really run just like fossil fuel-baed gasoline or diesel? 

It’s just a tuning matter, it's not a problem of hardware. Bottom line is they are "drop in."