This is how car manufacturers are looking for more range for electric cars

There are many ways to increase the range of an electric car. The simplest solution: install a larger battery with more energy. Downside: The car becomes more expensive and heavier. So it remains to save energy. Heating or air conditioning can be turned off. But who wants to freeze or sweat? 

On the vehicle side, energy consumption can be improved through several adjustments. For Markus Lienkamp, professor at the Chair of Automotive Engineering at the Technical University of Munich (TUM), these are several aspects. A lightweight vehicle ensures low rolling resistance, as do low rolling resistance tires.

"But braking systems and wheel bearings with low friction also increase the range," he says.

Economical auxiliary consumers such as heating, air conditioning, and lights further reduce consumption.

Therefore, more and more manufacturers are working on the most efficient drive possible. The times when two and a half ton electric cars consume up to 30 kWh per 100 kilometers are soon to be forgotten. European manufacturers aim to significantly reduce power consumption with new vehicle generations. 

Low power consumption is the focus

BMW and Mercedes-Benz are presenting new vehicle platforms this year for particularly energy-efficient models.

"We are approaching 12 kWh per 100 kilometers," says Oliver Zolke, Project Manager Development MMA Architecture at Mercedes-Benz.

This should enable the model to drive up to 750 kilometers. According to Markus Lienkamp, most development potential currently still lies in the electric motor and power electronics.

"In general, electric motors already operate very efficiently. Drives with an efficiency of up to 95 percent are possible, but at some point, that is the physical limit; an electric drive cannot operate more efficiently."

Can a theoretical value be implemented in practice?

The 12 kWh per 100 kilometers is an ideal value according to the standardized WLTP driving cycle.

"In reality, however, it is hardly achievable as it is driven under low loads and speeds, and without auxiliary consumers, at moderate temperatures," says Lienkamp. "Customers usually drive faster, especially on highways, and also drive in cold conditions."

This increases consumption. Therefore, the 12 kWh is more of an optimistic value. He sees a good real consumption at 15 kWh per 100 kilometers.

In the new Mercedes-Benz MMA architecture, on which the first of four models will be launched in the fall, engineers are developing all components towards low power consumption.

"Our focus from the beginning in development was on efficiency. Because 55 watts less consumption means 1 percent more range," says Oliver Zolke.

With low-resistance tires, Mercedes aims to save ten percent energy, and a two-speed gearbox ensures low RPMs of the electric motor at higher speeds from around 70 km/h—thus reducing energy consumption.

With four recuperation levels, the battery can be recharged with energy. Recuperation refers to the recovered deceleration energy when the foot is off the accelerator.

"Almost all braking maneuvers in everyday life are handled through recuperation," says Oliver Zolke.

This is finely tuned and works particularly efficiently. This means that the maximum energy is generated just before the wheels lock—up to the ABS control limit. 

“At some point, physics reaches its limits”

For years, Tesla has shown how efficient electric cars can be built: The Model 3 has a consumption of 12.5 kWh in the WLTP cycle. A Lucid Air Dual Motor Pure RWD now requires 13 kWh per 100 kilometers, as does the much smaller Fiat 500e RED. Markus Lienkamp does not believe that consumption in typical passenger cars can be reduced to below 10 kWh per 100 kilometers:

“At some point, physics reaches its limits.”

With BMW's new vehicle platform, Neue Klasse, the manufacturer reduces the consumption of every component. It starts with the control units, internally called “superbrains” at BMW. Instead of a multitude of individual control units as before, BMW now relies on four central computers.

“For us, it’s important not to waste a watt-hour. There's nothing more frustrating than developing a large battery beforehand and then squandering the energy with inefficiency,” says Frank Weber, head of development at BMW. Today's batteries are already too large anyway.

To reduce consumption, all components in the car are needed. The computer calculates up to 1,000 times per second in the control unit for driving, making it ten times faster than previous systems. As a result, power electronics, the battery, and the electric motor operate even more efficiently together. 

The electric motor recuperates until just before the ABS control range, works during braking or coasting in curves, and thus ensures a range extension of about 15 kilometers.