How Powerful the Brakes Really are...

It was never meant to replicate the Lexus situation. WOW. It was meant to show that the brakes in a car, in good working condition, will stop that car...even if it has over 500 hp in open throttle conditions from highway speeds.

The test was done on the C&D test track, which is flat as opposed to having a 2.5% incline that the Lexus drove down, and the C&D test was done on a Camry, not a Lexus. C&D also did tests on a much higher HP car (ie, about 560 hp). Geez.

The C&D test on the Camry would still stop from 70mph, even if fully loaded. The only difference would be longer stopping distance because a fully loaded vehicle would have about 12% greater acceleration force due to greater mass. But even if you don't believe a fully loaded vehicle would be stopped by the brakes (I really don't care what you believe), at the very least, brakes in good working order would EASILY pull the speed down from 70 (or 100mph) to much, much lower velocities. At impact, the lexus was estimated to be going about 100mph...that tells me the brakes were compromised (read all the prior posts on this...I'm not going to repeat what has already been discussed many times), and had minimal, or no affect in slowing the car down.

 

I'm comparing fully loaded Camry, with partially loaded (ie C&D test) Camry. The person I was responding to said the test was unrealistic because it wasn't fully loaded (among other reasons). My point was, even had C&D done the test fully loaded, with 4 people...the added force would be about 12%, and I have no doubt the car would still have been been brought to a stop...just at a longer stopping distance.

Yes, only about 12% force difference. I assumed 4 people @150lbs each in a Camry. In the C&D test, they had 1 person, the driver. Estimated passenger weight difference ~ 450lbs on a 3500 lbs car (ie, Camry).

But here's the bottom line (as far as I'm concerned)...Had C&D tested a 2009 Lexus, loaded it with 4 people, run it up to 100 mph....I'd bet my next paycheck the car would stop...and if it didn't, the speed would most certainly be under 20 mph (maybe less). Had the driver of this Lexus been able to get it down to speeds approaching 20 mph, no doubt this tragedy would have had a completely different ending... IMO, something eles happened? That's my point.

 

Agree on some cars, and STRONGLY disagree on others. I already gave you an example (my older subaru), and another person gave you another example (I think Cady) where steering at higher speeds was very difficult with loss of power. But believe what you want.

Disagree. Again, it depends on the particulars of the vehicle. One model does not fit all possible scenarios.

That would be your choice, and for your car, that may make perfecet sense. But clearly, the folks at C&D, who are speaking in general terms, would disagree...and so would I. Even of you doubt what i am telling you, I really don't think you know more than the test forks at C&D.

Finally, we agree. This thread is not aimed at the Prius.

 

Really, take it up with Car & Driver. Write them an email to get the clarification you seek. You clearly think you know more than the staff at C&D, and you obviously have your own view of things...and that's fine. But it's not my job to try and convince you of anything.

 

There are a number of different metrics when evaluating brakes, but the one that's most important to me is, stopping distance. That said, the stopping distances are not too dissimilar. This table is some site over in Europe, so things are in km. But the list is pretty extensive, and you can do your own comparisons.

movit - the brakes stopping distance table



FYI (from Edmunds on a few examples)-

60-0 stopping distance for BMW 328i: 110 ft.

60-0 stopping distance for Prius G3: 118 ft.

60-0 stopping distance for Audi A4 Quatro: 123 ft

60-0 stopping distance for Land Rover LR4: 126 ft.

http://www.edmunds.com/bmw/3series/2008/testdrivemanual.html

http://www.edmunds.com/toyota/prius/2010/testdrive.html

2009 Audi A4 2.0T Test Drive on Edmunds.com

http://www.edmunds.com/landrover/lr4/2010/testdrive.html

 

I currently have a Jag and a BMW...as well as a Prius. I can't speak to other Toyota products, but I'm happy with the brakes on the Prius. If anything, I think they are a bit on the "grabby" side, and actually, have to press lightly so i don't end up lunging forward...that's also when i experience this braking issue over pot holes. That is, while pressing lightly, I can sometimes feel the brakes let up slightly...but when i push harder, I have no problems.

 

What does "stopping distance mean"? Now that's fuunny. Is this a serious question? If you really don't know, and want to learn more on the methodology of this test, read this:

http://www.oregon.gov/ODOT/TD/TP_RES/docs/Reports/ComparsionOfSkidResist.pdf

Standard stopping distance measurments, that are reported by car magazines, and independent testing organizations, perform this test under full/maximum pressure (ie, panic stop conditions). Brake peddle down as far as it will go. The numbers are not meant to be absolute (because such factors as reaction time comes into this), but is useful for relative comparisons.

Yes, the Prius brakes do have a different feel from either my Jag or BMW...but the test results would indicate the Prius brakes are more than capable of beating an Audi A4 Quatro or Rover LRX in 60-0 mph braking tests....even if they do feel "different".

 

To add to this, and is the point that fuzzy fails to grasp is - The comment by C&D, regarding the reason why they do NOT recommend turning off the power to the car while still trying to navigate...is because when the power is turned off, that will cause some cars (not all) to partially lose steering and/or braking. That is, both, or either steering and/or braking effectiveness could be compromised by turning off the engine. It was C&D's recommendation that turning off the car's power was the last thing you should try in a chain of steps they recommend. Obviously, if all the other steps they had recommended don't work, and you're still flying down the road...then by all means, turn the car off.