One of the greatest advantages electric vehicles have over internal combustion vehicles is their ability to recover energy while slowing down. Instead of wasting the kinetic energy, EVs convert it to electricity, feeding power back into the battery. You can’t do that with gas cars. Once fuel is burned, it’s gone, you’re never getting it back.
But there’s another way to conserve energy: coasting. That’s when you get up to speed and then let the vehicle glide freely with minimal power inputs. So, which technique is better for squeezing the most range out of an EV? Regenerative braking or coasting? I decided to try and find out.
Volkswagen loaned me the ID. Buzz last week for this test. I drove it in New York City and its suburbs for roughly 250 miles, comparing efficiency in different conditions. The ID. Buzz offers regenerative braking with two modes: a default "D" (Drive) mode for light coasting and a "B" mode for more aggressive braking. (In general, the Volkswagen Group is skeptical of true one-pedal driving like many EV makers offer, so B mode kind of replicates that experience—until you have to use the brake pedal to stop.)
In short, I found that regen was more effective overall but it wasn’t always the best way to maximize range.
The ID. Buzz gets 86 kilowatt-hours of usable battery capacity. The EPA-rated 231-mile range on the AWD trims gives it an efficiency of 2.7 miles per kilowatt-hours. That’s not what I observed in either mode, but it was somewhat in that territory.
The impact of coasting on efficiency depends on several factors: topography, aerodynamics, vehicle weight, driving style and even weather. It’s the most effective on flat terrain and gentle downhill slopes. But if you live in a hilly area, coasting loses its edge, since the energy saved going down gets used while climbing back up. Then again, that applies to regen, too.
The ID. Buzz, even though I love its design, has the proportions of an average Manhattan apartment. It’s tall, boxy and not exactly aerodynamic, even though its surfaces are relatively smoother than other vans.
It measures 195.4 inches long, which is nearly five meters. It has a curb weight of a whopping 6,197 pounds (2,811 kg), of which the battery alone accounts for 1,230 pounds. For reference, the base Chrysler Pacifica is 1,700 pounds lighter. That means the ID. Buzz doesn’t slice through the air, but once it gets going, it’s like a boulder barrelling down the hill. It requires plenty of stopping power—it gets disc brakes upfront but drum brakes at the rear, which is a shame for something that’s so heavy.
By default, regenerative braking is off. To activate it, you have to twist the column-mounted gear selector from “D” to “B.” Even then, the regen is mild, not the aggressive one-pedal driving experience found in some EVs. You’ll still need to use the brake pedal to come to a full stop.
Also, regenerative braking never truly deactivates. Sure, the vehicle coasted every time I lifted my foot off the throttle. But pressing the brake pedal still activates recuperation. I also drove in Comfort mode. That’s how this van is meant to be driven. It doesn’t like being hustled. And besides, most owners will likely drive it in Comfort mode, too, especially if they’re ferrying passengers.
All these variables influenced the efficiency numbers I calculated and the ones indicated by the vehicle’s computer.
On a bright sunny day with temperatures hovering around 50 degrees F (10 degrees C), I observed a maximum efficiency of 3.2 miles per kilowatt-hour while coasting. That’s around suburban New York City roads. That number tanked when it started pouring and I got stuck in traffic while returning to the city.
Coasting is inefficient in stop-and-go traffic, but on open roads, the ID. Buzz required minimal throttle inputs to keep going. Over 103 miles of driving in mixed conditions, of which 70% of the drive was in NYC suburbs and the rest in the city, the calculated efficiency was 2.1 miles per kilowatt-hour while coasting. The efficiency indicated by the on-board computer was 2.4 miles per kWh.
For reference, the Tesla Model Y and Model 3 deliver well above 3.0 miles per kWh, but they aren't brick-shaped like the ID. Buzz. It’s also worth noting that this is based on the energy delivered by the 350 kW Electrify America stations. It does not factor in the energy losses, so the energy accepted by the vehicle was likely slightly lesser and hence the efficiency marginally higher than calculated.
After switching regenerative braking on, the efficiency improved noticeably.
Over 90-odd miles of driving in the same mixed traffic conditions, the calculated efficiency was 2.5 miles per kWh and the indicated efficiency was 3.0 miles per kWh. In the city, I observed this number climb to 3.2 miles per kWh, identical to what the ID. Buzz delivered while coasting on open roads.
So even though regen was better overall, the best way to squeeze the most range is to use a bit of both.
Regen shines in stop-and-go traffic, and coasting is great on open roads. Instead of keeping your foot planted all the time, you can let go if road conditions allow the vehicle to cruise smoothly.
Some automakers allow a higher degree of customization with their regenerative braking settings. Arguably chief among them is the Hyundai Motor Group, whose EVs have multiple strength levels set with paddle shifters on the steering wheel. As many tests have shown, including the video below, using regenerative braking is the best way to maximize around-town efficiency. On the highway, you may prefer to just coast instead.
Also, remember that anticipation and defensive driving can help your efficiency. If you see brake lights on the cars ahead, don’t accelerate and then slam on the brakes when you get closer—that’s just a waste of electrons. You don’t have to hypermile like a saint, but smart driving habits benefit both your wallet and your vehicle in terms of maintenance and repairability.
All said, it’s impractical to switch between coasting and regen every single time. Unless you’re laser-focused on eking out every last mile of range from the battery, leaving regen activated should suffice for the majority of drivers.
Have a tip? Contact the author: suvratkothari@insideevs.com
