Energy recovery or coasting? Volkswagen has it clear with its new ID.4

In an electric car, the efficiency of the energy recovery system is key. Much of an electric car’s ability to deliver its advertised range depends on this system.

One of the questions that can arise in many situations, mainly when the driver lifts their foot off the accelerator without needing to use the brakes, is deciding what is more worthwhile: having the regenerative braking work, or letting the car coast.

In the first case, the electric motor starts working as a generator; energy is thus recovered and returned to the battery, but the car tends to lose speed faster, so you will also have to accelerate again sooner. In the second case, no energy is recovered, but the car travels more metres relying solely on the momentum it was carrying.

We could even draw an analogy with a combustion car, when we wonder whether it is better to lift off the accelerator when going downhill, or to shift into neutral. When you lift off the accelerator, the engine uses no fuel because it is disconnected; but with the transmission still engaged, the car coasts a shorter distance and loses speed sooner than if we shift into neutral. In neutral the car travels further, but the engine remains connected and keeps consuming fuel, although a minimal amount, the amount needed to maintain idle.

The intelligent energy recovery system of the Volkswagen ID.4

Returning to electric cars and the Volkswagen ID.4, the German brand’s answer to this question is as follows: the strategy depends on each case and each model. For this reason, unlike some electric cars that always activate energy recovery mode when you stop accelerating, Volkswagen gives priority to coasting, since converting energy involves a series of losses.

What Volkswagen does in the ID.4, and also in the ID.3, is configure the system so that, whenever driving with the gear selector in “D” mode, the priority when you stop accelerating is to activate coasting mode, disconnecting the motor from the transmission and recovering no energy. Here you can read the road test of the Volkswagen ID.3.

If from here the driver wants to lose more speed, they can activate the energy recovery system by lightly pressing the brake pedal. Then, and for decelerations of up to 0.25 g, which correspond to most everyday driving situations, the electric motor handles the deceleration through regenerative braking. Only if greater braking force is demanded through the pedal are the hydraulic brakes activated.

How to use B mode on the gear lever?

The Volkswagen ID.4 comes as standard with an ECO assistant, which analyses data from the navigation system and the vehicle’s sensors to help the driver drive efficiently. This system alerts the driver, for example, when approaching an area where the car will need to slow down. It does so through pulses in the accelerator pedal itself, and the system takes care of deciding whether, once the driver lifts off, it is worth activating coasting or recovering energy.

In addition, the driver can switch between “D” and “B” on the gear lever at any time. When using “B” mode, the car always recovers energy when we lift off the accelerator, so there is noticeably more retardation than when we do so with “D” selected. However, energy recovery in “B” does not remain active until the vehicle comes to a complete stop.

A limit of 0.13 g has been set, which is enough for the deceleration to be clearly noticeable, so the driver does not feel that the accelerator pedal is being used to both accelerate and brake the vehicle. This is a completely different approach to, for example, that of the e-pedal of Nissan, which other electric cars such as the BMW i3 also use.

Some versions of the W ID.4 also allow the driver to influence the way the system alternates between coasting and energy recovery. In cars equipped with the Plus sport package, the “Sport” program allows energy recovery to be activated even with the gear lever in “D”, although not with the same intensity as when “B” is selected. Always bearing in mind that if the battery is sufficiently charged and cannot store any more recovered energy, the coasting system will be activated.