Accidentally Turned Off Engine

My instinctive reaction would have been to use the parking brake to stop. I have noticed that brake pedal pressure required on newer vehicles with engine off is far greater than I expected.

"I have noticed that brake pedal pressure required on newer vehicles with engine off is far greater than I expected."

Bingo! I’ve tested my Insight by turning the key off going down a slight incline in neutral at about 20 mph, and after 3 brake pumps it was MUCH harder to slow the car. That’s good advice to be prepared to use the parking brake, i.e., practice doing it. I like the hand lever type because I can hold the button in and do a fair job of modulating the rear brakes.

Today’s little motors just don’t have the vacuum of the old V8s. The manufacturers need to compensate by designing boosters with larger diaphragms… which means when the engine’s off you lose more assistance. 2 PSI of pressure (vacuum) on a diaphragm of 12 square inches is 24 pounds of assist. 1 PSI is 12 pounds of assist. To make it 24 pounds again, one needs to double the surface area of the diaphragm.

I admit that I’m just wildly guessing here, I have no data to back me. And I also haven’t thought this through thoroughly. I could be totally wrong.