Tuesday, March 16, 2010

About that Cali Prius

I don't know what to think about this. On the one hand it entirely possible that an electronic fault occurred in such a manner that this fellow could go 30 miles without being able to stop his car. It's possible. A computer can have a process go haywire while the rest of the system keeps going fine.

I don't know enough about the systems on the Prius but I have a few questions:

1) What were the conditions of this fellow's brakes prior to this incident? I work on cars as a hobby and have many discussions with my mechanic about how people run their brakes down to the back plate and do irrepairable damage to their rotors. And front brakes, which the reports say were the most worn, are the first to go due to weight shifts to the front of the vehicle upon braking.

2)Was the brake regenerative system working? My understanding is that when the brakes are applied, there are magnets at the wheels that take the rotational energy of the wheels and converts that to electrical energy to charge the batteries. I understand that the Tesla roadster's system is so aggressive that merely taking one's foot off the gas causes that system to kick in to the extent that Tesla has the brake lights come on anytime the accelerator is depressed. So does the Prius operate this way and if so, is there any record of that system being active? If so I would think that 30 miles of brake riding would have given the battery a nice charge.

3) How did the officer at the scene know that the driver was 'standing on the brakes"? I don't know about you but I cannot see the feet of the driver in the car next to me. We only have the man's word that he was in fact ONLY pressing the brakes. I have driven behind people who have locked their brakes, it is not a pleasant smell and being a convertible owner I can tell you that I can smell brake lock at least a half mile away from the vehicle that is experiencing it. Speaking of brake lock even if the front brakes failed, the rear brakes are supposed to be able to stop a vehicle as per federal regulations. Yes it will take longer, but they are supposed to do so as per fed reg. So that leads to my next question.

4) What's up with the hydraulics? My understanding of all these computerized cars is that even if an electronic part fails, the hydraulic system is supposed to work as a fail safe. Is braking on these vehicles at a point now where braking is no longer done by the driver? Why not? It is one thing for a computer to be able to actuate the brakes in case of emergencies such as loss of traction or the like, but complete decoupling of brakes from the foot sounds like a serious liability issue to me. Think about it. If you are not physically responsible for actuating the brakes, then brake failure can be attributed to the vehicle with no liability on the owner. This case underscores it. Can Toyota prove that it's system worked at the time of the incident beyond reasonable doubt? Absolutely not. In a foot activated hydraulic system it can be demonstrated beyond reasonable doubt that a driver used or did not use the brake. It can be proven beyond reasonable doubt that the hydraulics were to spec or not.

5) About those electric motors. If I read the schematics correctly, the Prius has electric motors that drive the wheels directly. Is it entirely possible that the engine itself was deactivated but the electric motors, which are designed to run even if the IC engine is not, kept running? My understanding is that the electric motors on these things produce 268ft/lbs maximum torque at low rpm ( for comparison my 1997 Z3 with a 2.8 liter engine has 190 hp/ 206 lb/ft torque. My 318i with a 1.8 liter 4 cylinder has 138 hp and 129 lb/ft torque.)

So combined the electric motor and the IC on a Prius could top 350 lb/ft which is sports car territory and shoddy brakes could possibly be overcome by a runaway drive train though for 30 miles at 90 mph? I doubt it.

In this case all the driver has to do is point to the Toyota recalls and stand his ground. At this point I see nothing that can be proven in court that points to his negligence or fraud because no one can prove that his computer wasn't working at THAT moment in time.