Engine Braking for Going Down Hills Safely and Saving the Brakes

"We love our rental car. The only problem is that it accelerates uncontrollably going downhill, and we have to keep our foot on the brake the whole time."
That's an actual (not made up!) comment, sent in an email by two customers who rented a car from Frank's Friendly Cars Maui Car Rental. They stayed Upcountry in Kula, near the 4,000 foot elevation on Maui, for three weeks, driving up and down the long steep incline of the Haleakala Highway every day. Judging from their comment, in those three weeks they probably took six months (if not more) off the life of the brakes, which were brand new, installed only six weeks before their rental.

Anyone following the news has heard a lot about "uncontrolled acceleration" in the last year. In fact, it was "uncontrolled acceleration" that forced a recall and public scandal for the Japanese auto manufacturer Toyota.

However, there was absolutely nothing wrong with the car driven by this customer. It was a 1997 Hyundai Elantra, and it was never the subject of any braking or acceleration related recalls.

The real problem was that these customers were missing a very important (if not absolutely crucial) piece of the safe driver's repertoire. How can you keep a car with automatic transmission from "accelerating uncontrollably" going downhill? That's easy. You use engine braking.

For anyone who was not paying attention during that particular session of their Driver's Education class, here is a reminder of how to use engine braking, with illustrations, courtesy of the Toyota Corolla Owner's Manual. This time, please pay close attention.

Using Engine Braking

To use engine braking, you can downshift the transmission as follows:
  • Turn off the the overdrive switch. The "O/D OFF" indicator light will come on and the transmission will downshift to the third gear. [Note: The overdrive switch is the small button on the left side of the gear selector lever, clearly labeled in the illustration on the right.]

  • Shift into the "2" position. The transmission will downshift to the second gear when the vehicle speed drops down to or lower than the maximum allowable speed for second gear, and more powerful engine braking will be obtained.

  • Shift into the "L" position. The transmission will downshift to the first gear when the vehicle speed drops down to or lower than the maximum allowable speed for the "L" position and maximum engine braking will be applied.
"2" ....... 68 mph
"L" ....... 38 mph
That's it, straight from the horse's mouth. Please refer to the illustration (click on it to make it larger) to see clearly the different gear selector positions, as well as the location of the Overdrive button on the side of the gear shift lever.

What if you're not driving a Toyota? Most, if not all, cars with automatic transmission have a very similar feature. Chances are that any car you're driving has this feature too.

Engine braking is essential if you want to drive safely going down long hills, and it's absolutely essential for extending the life of the car's brakes.

Drive safely! And next time, when you are having a problem with uncontrolled acceleration - or anything else, for that matter - in your rental car, please call us right away, instead of waiting three weeks. Doh!