In the last episode, we showed that you can stop a Prius with a wide-open stuck throttle with little drama, even if you forget to shift into neutral before stomping on the brakes. It's all down to the brake override system that's installed in every Toyota hybrid. The electric motors within, you see, can't simultaneously provide propulsion and regenerative braking, so the software has to pick one, and it picks the brakes.
We showed how this works in last week's video. But that demo was filmed on a public road, so we didn't install our instrumentation or come to a complete stop when the cameras were rolling.
To do that, we brought the Prius along to the next scheduled track test day to get some numbers comparing a normal stop to a wide-open throttle stop with the transmission in "D" throughout.
As you can see, there was no meaningful difference in stopping distance. The standard 60-0 stop took 134 feet, and the wide-open throttle stop we made right after it took 135 feet. The tiny 1-foot difference falls within normal variation for sucessive stops like these.
The full-throttle stop required no more effort than a regular stopping distance test -- it was easy.
The Prius' brake override system is quite effective and it doesn't require a lot of driver effort to engage. Push on the correct pedal with anything approaching a desire to stop and our Prius will do it.
Dan Edmunds, Director of Vehicle Testing @ 66,301 miles
dino6 says:
12:19 AM, 03/22/10
These kinds of tests would mean something if you tested about 10,000 Priuses. The fact that you can get a test result from one Prius does not mean anything. After all, the UI problem does not affect ALL Toyotas. The worry is that it affects enough of them.
pat1usmc says:
04:02 AM, 03/22/10
^Agreed. Enough with these tests already. I'm sure they get you tons of publicity but they mean nothing. Of course this is what normal Priuses should be doing. There was never ever any debate over that.
cynic783 says:
05:00 AM, 03/22/10
Please continue these tests on as many different Prius' as you can get your hands on. Also, try it on a Camry.
There is an irrational fear of computers here that some are playing on, and your efforts are helping to expose that.
1487 says:
05:37 AM, 03/22/10
we got the message IL- Toyota owners are inept. PLEASE stop these stupid emergency braking demonstrations to prove that any Toyota can be stopped by slamming on the brakes. WE GET IT. I don't think anyone here is even arguing that Toyotas can't be stopped so I don't know whom you are trying to convince. I'm sure your Toyota ad dollars are safe at this point.
brn says:
05:59 AM, 03/22/10
IL, next could you try to stop a Prius with an elderly person driving? After that, a female? Then let's do it when being followed by an SUV? Don't forget to test it with a State Trooper next to you.
/s
Stop beating us to death with your irrelevant tests! You're not proving squat.
mheikka says:
06:22 AM, 03/22/10
I think these tests/posts are useful and important. Even if the sample size (1) is statistically irrelevant, it does debunk many of the rumors/assumptions that are flying around out there, like:
1. A hybrid car can out-accelerate its brakes
2. Regenerative braking systems (common to hybrids) don't work well
3. The hybrid "computer" can shut off the brakes and prevent you from stopping the car
4. The car will "flip over" if you put it in neutral at speed (apparently one person on earth held this belief.)
5. Hybrids, in general, are dangerous, and we should keep driving our sub-20mpg gas eaters.
6. Operator error or lack of education is playing no part in these "crazy hybrid" stories
7. These stories are nothing like the "crazy Audi" hysteria we had a couple of decades back
8. The "sudden acceleration" issue plagues every hybrid
9. A car that suddenly accelerates will leap to 85mph plus
While it is a terrible tragedy that some loss of life has occured due to Toyota's design issues (pedal clearance/floormats, etc.) the news media-glamorized reports of crazy hybrids need to be debunked. Edmunds is performing a public service by performing real-world tests and taking real-world measurements (not hiring "scientists" and "engineers" to rig an out of control car for good footage sake.)
Half of the Prius problem is that vehicle "operators" don't know what to do in the event of a control malfunction with their cars. Any education here is invaluable and will save lives.
hybris says:
07:01 AM, 03/22/10
I think we have learned all we can about the run away Prius thing can we drop the subject or do these tests on something else not Toyoda like the Ram or the Flex hell add the M3 and 750 for kicks otherwise lets stop beating the dead horse here.
s1gins says:
07:01 AM, 03/22/10
The sample size is 2, since I have performed the same tests on my Prius (2008)...this is valuable since a lot of consumers get their information from Edmunds which counters the morons in the MSM that have no clue about cars.
brn says:
08:11 AM, 03/22/10
mheikka, you're list is full of stuff that 99% of people don't believe anyway. The only ones spreading most of those rumors are the ones that want to debunk them.
The only two worth discussing are #3 and #8. Neither of which does this test prove or disprove. Yet, Edmunds felt the need to repeat the test with more cameras that don't show us anything.
1487 says:
09:03 AM, 03/22/10
s1:
Who in the mainstream media said Toyotas cant be stopped if you slammed on the brakes? Please provide an example or two. ONE guy made the news for claiming his car wouldn't stop and his story has been exposed. There is no reason for IL to keep beating this dead horse. WE ALL AGREE that any car can be stopped if you slam on the gas pedal. This is really venturing into the realm of being little more than Toyota PR disguised as "consumer advice".
bimmerjay says:
09:39 AM, 03/22/10
"WE ALL AGREE that any car can be stopped if you slam on the gas pedal."
I tried that this morning and it didn't work...
creeper says:
10:28 AM, 03/22/10
1487-one guy whose story was exposed, and another guy who managed to kill everyone in his loaner car
evil1487twin says:
10:48 AM, 03/22/10
Thanks Edmunds for your good work trying to understand what is going on with unintended acceleration. I know most Toyota owners love their cars and don't want to be afraid to enjoy them! It's great that we can all enjoy whatever car or truck appeals to us, we have that choice.
joefrompa says:
11:52 AM, 03/22/10
If I read Edmunds right here (despite people saying "Maybe this doesn't represent all Prii!"), then Edmunds just said it's physically impossible for the car to brake and be giving throttle simultaneously. Not impossible due to software, but actually mechanical needs.
Maybe I read them wrong? But if not, this is important.
The question is: Can the throttle get stuck at wide open while simultaneously telling the braking system to NOT switch to regenerative mode?
This is distinctly different from just the throttle sticking at WOT alone.
firstwagon says:
11:56 AM, 03/22/10
I think the test is important. It shows that even if there is a malfunction and the car goes full throttle, you can still stop it with no problem. I have yet to see any evidence of anything happening to Toyotas that this test doesn't cover.
Amazing how many people I meet that would never drive a Toyota now. They seem to believe that brake failure combined with the throttle jamming full on is happening all the time everywhere. When I ask for examples or details the response you get is "Oh I heard it somewhere".
I realize the "we hate Toyota" crowd are loving this but it just reeks of BS.
1487 says:
12:37 PM, 03/22/10
"1487-one guy whose story was exposed, and another guy who managed to kill everyone in his loaner car"
so based on those two stories IL feels they have to go on a crusade to prove that Toyota's brakes are sound? I am asking whom in the media or on this site is questioning the performance of Toyota's braking systems. Have not gotten an answer yet.
"Amazing how many people I meet that would never drive a Toyota now. They seem to believe that brake failure combined with the throttle jamming full on is happening all the time everywhere. When I ask for examples or details the response you get is "Oh I heard it somewhere"."
Thats the same mentality that has helped Toyota become so successful. Cant really get mad now just because many car buyers/owners are lemmings. Consumer reports and Toyota would have you believe that if you buy anything other than a Toyota you are risking weekly breakdowns. There is plenty of evidence to the contrary but Toyota's bottom line benefits from ignorant consumers.
creeper says:
01:02 PM, 03/22/10
no, based on those two stories the mass media outlets have decided to make a martyr of toyota even if it means ignoring base journalistic processes (you know, trust nobody, question everything). as far as whom is questioning toyota's brake systems, look to fox news, they were among the first to jump on the 2010 prius brake complaint scandal.
joefrompa says:
02:18 PM, 03/22/10
1487 - I think the general media have been crucifying toyota based upon very questionable singular events. Much like they did with Audi in the 80s and Ford Explorers in the 90s. And what TV "news" show was it that rigged a truck to blow-up?
I.L. is providing a nice tested environment to bring some realism to the hair-pulling going on in the world. I'm glad they are doing it, personally.
Just my take.
bimmerjay says:
02:42 PM, 03/22/10
@evil1487twin,
I've noticed your unusually nice posts. I suppose the evil opposite of evil is... nice. So are you here to post the exact opposite of all of 1487's posts?