Firstly, driving in Low mode makes you a safer driver.
EV’s do not like rapid acceleration, positive or negative (deceleration). I generally try to envision a very flat bell curve for my driving. Slowly accelerate, maintain a safe speed, and don’t race to cut someone off or change lanes, and slowly decelerate. Driving in low mode or activating ‘L’ optimizes the battery energy recapture when slowing down. When I drive, I try to use my brakes as little as possible. My Mustang will decelerate on its own at a rate to recapture as much energy as possible.
Slamming your foot on the brake forces the car to stop quickly, which can be needed for safety in some cases, but in most cases, by simply lifting your foot off the acceleration pedal, the car will slow down, and you can safely maintain in traffic with only light taps on the brakes. When you stop quickly, all that momentum and all that energy must be stopped abruptly. That energy is coming back too fast for the battery to recapture it so that energy is lost.
My Mach-E lets me know how I’m doing so I can be a better driver for my cars battery. In the image, you can see that I get a score based on acceleration, deceleration, and speed. I can get this data for every trip I take. This post is focused on acceleration and deceleration, I’ll save speed for another time.
You aren’t rushing to try to beat lights and force an abrupt stop when you fail to do so. The same holds true for rapid acceleration. When you have your EV go from 0 to 60 in 3.8 seconds, it might be fun, and it really shows off the power of the car, but that rapid acceleration drains the battery much more than required. By slowly increasing speed, you allow the battery to pull a slow draw of energy, this will also allow for improved energy recapture. When you quickly accelerate, a force a large pull energy from the battery, most of that energy cannot be raptured.
I drive in Low mode ALL THE TIME!
This practice has been questioned by many with the argument that Low mode was designed for city driving but isn’t ideal for highway driving. So, I tested this extensively. When living in Chicago, I did frequent work trips and family visits to Michigan and got in a lot of highway time. Now, living in North Carolina, I continue to be able to test my theory on large, open (and better paved) highways. From an efficiency standpoint, I see a difference of 12.5% greater battery efficiency when driving in Low mode, from 2.4 miles/kWh to 2.7 miles/kWh. If you like to road trip in your EV like I do, then gaining 0.3 miles per kWh can mean fewer or shorter charging stops. The reason is the same as for city driving. Low mode optimizes energy recapture if you need to stop slowly for traffic flow or if there are hills, the battery will optimize energy recapture when going down a hill where gravity is helping to drive the car downwards, you don’t need the battery energy and, in fact, the battery can recapture energy while gravity does the work. I think about this like riding a bike. You don’t expend energy peddling while going down a hill, you let gravity do the work and save your energy for the uphill’s; let your EV do the same.