# Was the Prius acceleration real or not? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 15, 2010, 11:59am UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533 "2010-03-15T11:59:33Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [March 16, 2010, 2:28am UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/21 "2010-03-16T02:28:30Z")
> [@Czarcasm](#): > > [The latest from Toyota.](http://news.yahoo.com/s/ap/20100315/ap_on_bi_ge/us_runaway_prius) I’m not sure I understand their statements. They are stopping just short of claiming he committed a hoax, but admit that the brakes were worn down to bare metal and > [@](#): > > And the rest of the car was fine, the automaker said — the gas pedal was not slowed by friction, the floor mat was not even touching the pedal, and **a system that cuts the engine power when the gas and brakes are pressed at the same time was working**. which seems to imply that you can’t deliberately get up to 94 miles/hour by pressing the gas and brakes at the same time, doesn’t it? 😕 ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [March 16, 2010, 3:20am UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/22 "2010-03-16T03:20:57Z")
Look, every other case of “sudden acceleration” turned out to be driver error. Suddenly Toyota isn’t? The data indicates that there is a definite skewing by driver age. If this were a purely mechanical issue, then the reports would hit all ages equally (with adjustments for numbers of drivers in each age group). Here is [a graph of the US population by age](http://blogs.sas.com/jmp/uploads/agesextornado.png). Compare that to the chart of reported incidents by age. If this were a mechanical problem, the charts would roughly coincide – computers don’t discriminate by age. I don’t see how the miles driven distribution would be a factor – people drive all sorts of miles at all ages; any effects would cancel out. Same with age of the car – the cars are all in certain model years, so that is not a factor. Maybe there is a “base problem” that is hidden beneath the driver error. Remember, too, that you have a reporting bias in all driver error cases: the driver is much more willing to blame the car than himself. Years ago, when there was a similar case, the drivers described how the engine kept revving faster and faster as they stomped on the brake. However, Occam’s Razor (and investigation) makes it clear that this behavior perfectly describes what happens when you’re stepping on the gas instead of the brake. If a car revs faster and faster when your foot is on the brake, the most obvious (and common cause) is that you’ve mistaken the brake from the accelerator. And that is what’s happening with Toyota. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2010, 3:47am UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/23 "2010-03-16T03:47:17Z")
> [@RealityChuck](#): > > Look, every other case of “sudden acceleration” turned out to be driver error. Suddenly Toyota isn’t? > > The data indicates that there is a definite skewing by driver age. If this were a purely mechanical issue, then the reports would hit all ages equally (with adjustments for numbers of drivers in each age group). > > Here is [a graph of the US population by age](http://blogs.sas.com/jmp/uploads/agesextornado.png). Compare that to the chart of reported incidents by age. If this were a mechanical problem, the charts would roughly coincide – computers don’t discriminate by age. > > I don’t see how the miles driven distribution would be a factor – people drive all sorts of miles at all ages; any effects would cancel out. Same with age of the car – the cars are all in certain model years, so that is not a factor. > > Maybe there is a “base problem” that is hidden beneath the driver error. Remember, too, that you have a reporting bias in all driver error cases: the driver is much more willing to blame the car than himself. > > Years ago, when there was a similar case, the drivers described how the engine kept revving faster and faster as they stomped on the brake. However, Occam’s Razor (and investigation) makes it clear that this behavior perfectly describes what happens when you’re stepping on the gas instead of the brake. If a car revs faster and faster when your foot is on the brake, the most obvious (and common cause) is that you’ve mistaken the brake from the accelerator. And that is what’s happening with Toyota. There isn’t enough data to make any claims of age beyond maybe Prius cars are more likely to be purchased by older people than teenagers. But if you want to look at the numbers the majority of them occurred under 60 and were well distributed for such a low sample. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2010, 3:51am UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/24 "2010-03-16T03:51:30Z")
In what may be poor reporting they are saying that the engine would not rev up if the brakes are applied. That implies the drive-by-wire system would ignore the gas pedal input if the brakes were applied. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [March 16, 2010, 4:29am UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/25 "2010-03-16T04:29:31Z")
> [@RealityChuck](#): > > Look, every other case of “sudden acceleration” turned out to be driver error. Suddenly Toyota isn’t? [Not](http://www.leftlanenews.com/toyota-avalon-displays-unintended-acceleration-without-floor-mat.html) so. Plus, in the last really huge case, the NHTSA concluded that the _majority_ of unintended acceleration incidents in the case of the Audi 5000 were caused by driver error, but not all of them. > [@](#): > > Here is a graph of the US population by age. Compare that to the chart of reported incidents by age. If this were a mechanical problem, the charts would roughly coincide – computers don’t discriminate by age. It’s probable that a majority of these incidents are caused by driver error, which would result in a graph which trends upwards. I could have sworn that we pointed this out already. [QUOTE=Me, 11 posts ago] This. Assuming 50% of the incidents are actually driver error, which is a probable minimum regardless of whether the problem is real or not, obviously that’s going to factor into the statistic. In any case, 24 incidents is hardly a statistically significant number - and you would expect the curve to trend downward from the teens to about the 30-40 range, and upward from there. Instead, it trends sharply upward from the twentysomethings, and though my generation is unquestionably better than any which came before it we aren’t very good drivers, and we’re certainly not any less prone to accidental pedallage than 30-40 year olds. [/QUOTE] _ahem_ ---
**Author:** ![Gus\_Gusterson](https://avatars.discourse-cdn.com/v4/letter/g/85f322/32.png) [@Gus\_Gusterson](https://boards.straightdope.com/u/Gus_Gusterson)\ **Post date:** [March 16, 2010, 1:55pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/26 "2010-03-16T13:55:28Z")
> [@elfkin477](#): > > I’m not sure I understand their statements. They are stopping just short of claiming he committed a hoax, but admit that the brakes were worn down to bare metal and > > > [@](#): > > > > And the rest of the car was fine, the automaker said — the gas pedal was not slowed by friction, the floor mat was not even touching the pedal, and a system that cuts the engine power when the gas and brakes are pressed at the same time was working. > > which seems to imply that you can’t deliberately get up to 94 miles/hour by pressing the gas and brakes at the same time, doesn’t it? 😕 They said that the computer showed that he was pressing the gas and brake pedals alternately. He may have been flooring the car to get it up to high speed and then lightly applying the brakes to make it appear as if he were braking. When the car began to slow, he hit the gas again. He could explain the fact that the brake lights weren’t on all the time by saying that he took his foot off the pedal while pumping the brakes or because his foot slipped off the pedal because he was pushing so hard or some other excuse. ---
**Author:** ![MeanOldLady](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/meanoldlady/32/10737_2.png) [@MeanOldLady](https://boards.straightdope.com/u/MeanOldLady)\ **Post date:** [March 16, 2010, 2:08pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/27 "2010-03-16T14:08:11Z")
> [@elfkin477](#): > > I’m not sure I understand their statements. They are stopping just short of claiming he committed a hoax, but admit that the brakes were worn down to bare metal and which seems to imply that you can’t deliberately get up to 94 miles/hour by pressing the gas and brakes at the same time, doesn’t it? 😕 They said “In Sikes’ case, Toyota said it found he rapidly pressed the gas and brakes back and forth 250 times, the maximum amount of data that the car’s self-diagnostic system can collect.” Rapidly back and forth, so that suggests to me he was purposely accelerating his car, then braking. Err, what **Gus** said. ---
**Author:** ![Gus\_Gusterson](https://avatars.discourse-cdn.com/v4/letter/g/85f322/32.png) [@Gus\_Gusterson](https://boards.straightdope.com/u/Gus_Gusterson)\ **Post date:** [March 16, 2010, 2:24pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/28 "2010-03-16T14:24:37Z")
The fact that the front brakes were completely worn out is the one thing he has going for him in his story. Applying the brakes lightly wouldn’t have done that, nor would slamming the brakes in the absence of engine power making the wheels turn. The only way I can see the brakes being completely worn away if the car was functioning properly would be for him to have modified them before he set out. They say that the rear brakes and emergency brake were fine, so I’m guessing that he did alter the front brakes. I assume that someone has thought of that and it is being investigated. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [March 16, 2010, 2:30pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/29 "2010-03-16T14:30:57Z")
It sounds to me like Sikes didn’t realize that the on-board computer can actually record your actions. I think it also records speed. If they can then correlate when the car was speeding up with when he was pressing the gas they can demonstrate that he was always in complete control of the vehicle. The State of California should throw the book at him for false 911, endangerment and anything else they can come up with. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [March 16, 2010, 3:46pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/30 "2010-03-16T15:46:48Z")
> [@Gus\_Gusterson](#): > > The fact that the front brakes were completely worn out is the one thing he has going for him in his story. Not necessarily-we have no idea how much wear and tear the brakes had before the incident occurred. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2010, 7:40pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/31 "2010-03-16T19:40:17Z")
> [@Czarcasm](#): > > Not necessarily-we have no idea how much wear and tear the brakes had before the incident occurred. We know the brakes were used beyond their normal stopping capacity because the officer could smell them. A Prius has a 50 to 67 hp electric motor set so the hp and torque exist at a very low RPM. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [March 16, 2010, 7:42pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/32 "2010-03-16T19:42:39Z")
> [@Magiver](#): > > We know the brakes were used beyond their normal stopping capacity because the officer could smell them. A Prius has a 50 to 67 hp electric motor set so the hp and torque exist at a very low RPM. I wonder if tapping them a couple of hundred times in a very short period of time will get that effect? ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 16, 2010, 8:02pm UTC](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533/33 "2010-03-16T20:02:07Z")
> [@Czarcasm](#): > > I wonder if tapping them a couple of hundred times in a very short period of time will get that effect? I doubt it but power braking sure would. Either the computer was controlling it with an unknown flaw, the driver was controlling it or the pedal was stuck. [Previous page](https://boards.straightdope.com/t/was-the-prius-acceleration-real-or-not/532533.md?page=1)