Toyota Split Screen Braking Demo (Toyota Canada Demo)

It isn't a brake problem. It is a stuck accelerator problem at speeds beyond what the Prius can override with its brake design. The brake pedal swich is probably telling the ECU to "cut the engine to idle--I'm braking" but the ECU isn't listening. Yes, if we have to live with stuck accelerators then Toyota will have to upgrade Priuses with heavier-duty brakes.

 

Carolyn demonstrated that the Prius will stop from 70 mph in this video.

I believe the reason that the driver in San Diego could not stop is because he rode the brakes, rather than applying them fully at the beginning of the incident. The lesson to take away from this, if this happens to you, is to fully apply the brake and do not let up on the pedal until the car stops. Shifting into N will help also, which he did not do.

Driving 55 mph or less will help your mileage though, so if you want to do it for that reason, go ahead.

 

It's sad that demonstrations like this are felt to be necessary.

It's so frustrating.

It's like Toyota needs to run a campaign right now...Our Automobiles are Designed To Stop...or Toyota NOT moving forward, when you don't want to move forward....

That's a good demonstration, but why Toyota dealers or anyone thinks it's necessary is just a sad, sad thing.

 

This video at least and maybe all of them demonstrating the effectiveness of the Prius brakes are missing a very very serious point at high speed. When the brakes are applied they cut out the engine acceleration which drops to idle. This is why in this video the car came to a stop without effort. These stuck accelerator problems _are not_ dropping the engine speed to idle. If the brake disengaging the engine to idle _was_ working with a stuck accelerator pedal the Priuses would have all come to as quick a stop.

What you say about riding the brakes is likely true too. In this case the driver might have been riding on the brake while he was calling 911 and talking on the cell phone. This would likely cause then what happened when he went back to pressing very hard on the brakes when he was just below 90 mph against the constant acceleration torque of the engine.

The braking test should be done by Toyota with the brake assist disabled so that the engine continues to run and produce its torque at speeds over 75 mph minimum. I'll breath a lot easier at higher speeds knowing that proper brake application really does work. But I'm not willing to risk damaging my own brakes to prove or disprove the point and figuring out how to disable brake assist on a working Prius is an unknown.

I wish Toyota or Toyoda could jump into these threads.

 

I would add "and repeat the test a few times in succession".

That will reveal what the safety margins are which have been designed into the brake system.

 

I'd really like to know how the brake override of throttle is designed to work in the 2008 and the 2010 prius. I don't think we need to test it multiple times, since any reasonable person is going to have the car towed after the rare event of unintended acceleration. I would like it tested with warm brake pads, and slow initial application, with throttle override turned off. I'm not sure how throttle override can be turned off. 90mph seems like a great speed to test it at.

I hope we soon know what happened to that 2008 prius, so we know if it is an issue or not. The 2010 has stronger brakes, both regenerative and friction, and that may not be a fair test for earlier models.

I still feel safe that I can shift to neutral and brake with the unlikely event of unintended acceleration and failure of throttle override, but would like the other information also.

 

If the engine/MG2 are both driving the transmission and the brakes are holding the wheels back, I would expect "bad things" to happen to the mechanicals. So indeed Toyota should be performing these stress tests, not Prius owners.