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A Car With A Mind Of Its Own
mindriot writes "When Hicham Dequiedt, driving on a highway between Vierzon and Riom in central France in his Renault Vel Satis this Sunday, was overtaking a truck, his car began accelerating to 120 mph on its own, apparently due to a defect in the cruise control system. Stomping on the brakes proved pointless and, having a magnetic card for a car key, he could not cut the ignition. After calling the police from his cell phone who then attempted to clear the streets of any danger to him, in what he described as the most fearful event of his life, he raced down the highway for another hour before finally managing to stop the car. Read about the incident here or, in more detail, in this article by the German 'Spiegel' (translation). The case is still under investigation. Are we putting too much trust in the increasing number of electronic systems that our lives depend upon?"
Emergency brakes no longer exist. They are called parking brakes now, because they aren't designed to resist the torque of the engine, they just have enough power to hold the car from rolling, and even then, cars with manual transmissions are recommended to be put in either reverse or first gear to give additional resistance to keep from rolling.
The "emergency brake" is really just a parking break or "hill holding break" (designed to hold a car on a hill while engaging a manual transmission). Generally, enough force cannot be applied by the "emrgency brakes" to slow down a rapidly moving car without significant stopping distance. The "emergency break" also has the added disadvantage of ususally being attached to only two wheel breaks. Because of this, when applied at higher speeds, they tend to spin the car (usful for sheading speed only if you are an expert and have the road clearence - also usefull for "cool bootlegger moves").
Most every car made since the mid eighties has an electronic rev limiter on it. Attempt to rev past this limit, and the ECU will selectively cut fuel/spark to keep the engine speed under control.
;)
It's very accurate; +/- 20 RPM typically.
Sticking an engine with a stuck throttle into neutral will result in it banging off the limiter and making a lot of noise, but it won't overrev.
You can, however, MECHANICALLY overrev a manual transmission by downshifting into a lower gear while the wheels are turning at a faster speed than is otherwise proper for that gear. The wheels and the engine are mechanically connected, and downshifting to too low a gear will spin the motor up - no rev limiter can protect against this.
In certain BMW M3s, the transmission mounts get a little sloppy, and engine torque reaction under hard acceleration can rotate the transmission enough to move the shift gates. It's possible then to try and go 2->3 or 3->4, and hit 1 or 2 instead. This is invariably fatal to the motor. You will bring your pistons home in a bucket.
Depending on the contstruction of any given automatic transmission, it may or may not allow you to take it out of gear and go into neutral under throttle. If you are silly enough to be driving an automatic, this could be a problem - but anybody who'd buy an auto trans where a manual was availible would steal sheep - so you probably had it coming.
DG
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do not ever attempt to turn the ignition all the way off... In most cases you will lose both your power steering and your power braking.
Of course, power steering and brakes are specifically designed to work if the power component fails.
Losing power steering at a high rate of speed is not a problem - you turn the wheel very little when at speed. Power steering is only important when you're going very slowly and/or stopped.
You can easily lock up the brakes using your own leg power alone. Power brakes are just a vacuum booster, to make it way-easy to lock up the brakes. Without power, you just have to press harder. But it certainly is far from being impossibly difficult. And in any case, the vacuum ramains in the booster for some period of time. Just try it the brakes in your garage with the engine off, and you'll get a feeling for it.
Of course, many cars of the up into the 1970's didn't have power brakes or steering. And do you know what? They were steerable and stopable at all speeds. Basic steering and braking systems have NOT changed at all since then.
The only significant danger is enabling the steering wheel lock while turning off your ignation at speed. Watch out if you turn off your ignition while moving - you don't want to mistakenly LOCK your steering wheel while at speed.
Mod down parent.