Driving without brakes

Departments - Editor’s Page

October 14, 2016

Robert Schoenberger Editor || rschoenberger@gie.net

When gasoline crossed $4 per gallon in 2008, a lot of people tried changing how they drove to boost fuel efficiency. Look through automotive magazines from that summer or look through newspaper archives, and you’ll find lots of stories about hyper-milers – people who far exceeded the U.S. Environmental Protection Agency ratings for their vehicles.

Typically, driving advice was predictable – avoid quick starts, drive slower, avoid climbing steep hills if an alternative route is flatter. However, one tip stayed with me; drive as if your car doesn’t have brakes.

At its most basic, driving without brakes recognizes that drivers pay for every mile-per-hour of speed their cars accumulate. Accelerating a 2,500 lb car to 45mph requires a set amount of fuel, and if you regularly find yourself getting up to 45mph then slamming the brake pedal because of traffic, you’re wasting the fuel you spent getting up to speed. Gradually accelerating, leaving a sizeable space between yourself and other cars, then slowing down gradually by taking your foot off the accelerator and coasting toward a stop is a much more efficient use of fuel – an annoying way of driving for other cars on the road, but more efficient.

One hyper-miler said every time he had to hit the brake pedal because of traffic or emergency maneuvering, he felt like money was leaving his wallet and taking the surface of his brake pads with it.

With its upcoming Chevrolet Bolt electric car, General Motors (GM) hopes to introduce the idea of one-pedal driving to the mass market. As with hybrids and other electric cars, the Bolt features regenerative braking, technology that generates electricity from the act of slowing the car – energy normally lost as heat. The car has four driving modes, each with progressively more aggressive regenerative braking.

In three of the four modes, the Bolt will slow to a stop strictly based on how drivers use the accelerator. In those modes, the brake pedal will be for emergency response only. Without any other changes to the vehicle’s powertrain, GM engineers estimate that single-pedal driving will boost the electric car’s range by about 5%.

From experience, I can say driving without brakes works. I started minimizing brake use about 10 years ago, and I’ve found that it’s a practice that forces more situational awareness. You have to pay attention to anything that might slow you down, and to remember where stoplights and stop signs are so you know when to start coasting.

You quickly realize how inefficiently some people drive. I exit the freeway on my commute home on a steep hill that has a stoplight at the end of it. Even when the light is green, traffic generally forces drivers to stop at the top of the hill. Yet every day, I watch drivers accelerate up the hill, only to slam on their brakes at the peak. If I’m already going 65mph, that momentum is more than sufficient to get up the hill without spending another ounce of fuel.

Technology is improving fuel efficiency, but changes to driving habits could also have a big impact. GM appears to be combining the two approaches in its next electric car.