Brake Override in a BMW

Recently there ‘s been a lot of talk about brake override systems and how they work (and what automakers don ‘t have them). Recently the New York Times had a chance to watch (and feel) BMW ‘s system in action. Like other German makes, BMW ‘s system applies full braking while winding down the throttle when both are pressed simultaneously.

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  • Lee L

    I’ve been wondering about this ever since I saw they may require brake overrides in cars at some point. What happens if you take the car on the track and use heel and toe techniques? Are those days just over now? Or are the systems smart enough to tell the difference or maybe can be overridden like DST systems?

  • Rubber Ducky

    Unintended acceleration is not a problem with a manual transmission and brake override is unnecessary – push the peddle on the left to the floor, the clutch thingee, and the acceleration stops…. Heel and toe: clutch is in again when the accelerator is blipped. Can’t see an issue here…

  • Ben

    “the clutch thingee”? Ha ha!

  • Lee L

    Rubber Ducky, I hope you are right. I’m just not sure I trust the government to get this right since there seems to be such a groundswell to make something happen quickly.

  • Rubber Ducky

    Don’t think it’s rocket science. Toyota (the poster child for all this) has a closed culture and it is now biting them in the ass. Would take a high school science class about a week to test all failure modes. Problem seems to be an unwillingness at Toyota to make available its code reader.

    Is as much a market problem as one for the government to solve.

    As usual, BMW seems light-years ahead of the rice-burners.

  • chas58

    Gabe, I think you may have described this wrong. Most cars (excluding Toyota and Subaru for example) will cut the throttle if they detect that you have a foot on the throttle and gas at the same time. The car will not automatically give you “full braking… when both are pressed simultaneously.” Is “cutting the throttle input when both brake/throttle are applied” what you meant to describe? This would allow for full braking, but doesn’t imply you would get it if you were not mashing hard on the brake.

    For road and track, I do trailing throttle (heal & toe on brake/throttle simultaneously) and don’t get full braking as stated by Gabe above. The exception of course is if the car thinks (correctly) that I am doing threshold braking and it will maintain full pressure – as indicated by the second set of brake lights going on in the rear (I drive an e91).

    I did try pressing the start/stop button under full acceleration this morning, and the engine shut off after holding the button for 1 second. If my gas pedal was stuck, that is what I would do (and have done in my pre BMW past).

    Funny how unintended acceleration has never (since the Audi days) been a problem with people who drive manual transmissions.

  • chas58

    You know Gabe, I think the report is correct. If you accelerate and brake at the same time AND you make abrupt, forceful (i.e. panic) moves, the car will go to full braking (with much less brake pedal pressure than normal). However, if I make controlled calculated inputs (such as my heal/toe on the street or left foot trail braking on the track), the car responds smoothly as any other (I have a MT e91). BMW did their homework on this one!

  • BMW spends in excess of $200 per vehicle for this feature, and it adds some weight. Guess what- I’d rather spend the money, add the weight than having a metal shim if I was clueless enough to not know how to save myself… for some driving a BMW is a true blessing.

    In my first car (fully worked- I mean worked) 1973 VW Beetle, my dual barrel Webers would get stuck in full throttle now and again thanks to the linkage arm design- shift into neutral, turn it off and pull over…. Wow I am a genius!!

    My biggest issue with this whole acceleration nonsense is that people are not smart enough to realize that the brakes will work to some point then give out, as well as they can shift into NEUTRAL and cut the motor…… one of these days I will get around to writing an article on the dumbing down of society and how people are no longer smart enough to save themselves…. goes hand in hand with the electronic dipstick- people were too lazy/ didn’t know how to do it so the engineers needed to come up with a tell all button! I am sure the US gov’t is already coming up with legislation to make the electronic engine kill standard, just like Stability control.

    As usual BMW is ahead of the curve in providing the greatest safety features, kudos to BMW for helping those that can not help themselves!

  • JonPD

    Or better yet Michael drive a proper gear box and depress the clutch, move the gear into neutral, brake, then shut off the car.

    Another layer of technology to add mass along with a automatic gear box. Guess I am cynical but personally happier with my archaic gear box than any auto box.

  • chas58

    Michael – I don’t know how many cars I see with less than 10psi in the tires, but TPMS has to be one of the top inventions for the dumbed down society. Very few people tend to do any maintenance to their cars these days.P In my unintended acceleration experience (in a Jeep), my throttle was stuck. putting the car into neutral would have blown up the engine (no rev limiter), so I shut the engine off.

    I scratch my head about the news story yesterday (validated by highway patrol) about the prius driver that couldn’t stop his car. I have a hard time imagining that the Prius engine is more powerful than the brakes.

    I do think the start/stop button fad is confusing people like Prius & Lexus drivers. On the BMW at least, you do have to hold the button down (at least a second) to cut the engine. It was a little more intuitive when you just had to turn a key.