patentguy

Do you have ACC ?

donnie8300

Was going through a turn probably around 30ish or so a tight s bend and the car must hit some sensor. It seemed like I had hit something based on the pre brake weaning, but I think it’s prepped the brakes and warned me, didn’t actually hit anything. But these things ride low to the ground and hard to see given seating position. Checked car after and nothing hit. I think it’s some issue in the sensors.

Bassman51

I get the warning chime and warning message every week or so and there is never anything remotely close enough to be a potential problem - clear road ahead. Typically on secondary roads going 40-50 mph. I have ACC in my ‘20 992 and it’s always off in this situation. It hasn’t ever applied the brakes.

achilleas101

This thread got me curious, because i had no idea if brakes would be pressed or not. Looking at my build sheet, it would appear that it does. I do NOT have ACC.. but i dont know of this varies from model years or between S and base. I have a 22 4S.

Guzzgreg

Yup scared the hell out of me it was that hard.

nyca

So was the conclusion here that even the car without ACC, has the emergency braking capability as part of collision detection? The ACC feature equips the front of the car with that big "fish eye" sensor to monitor traffic ahead - absent that sensor, how does the standalone collision detection work?

kim9701

The Base C2 without ACC technical spec shows this

nyca

I don't really understand that description. Obviously, ACC "prevents most collisions" - since it stops the car in traffic before hitting the car ahead. Does the collision warning system do that? The wording above suggests it doesn't. Of course the other issue is - if you equip the car with ACC, and you aren't using it actively, I guess it isn't "preventing most collisions" either when its turned off.

I am trying to determine whether the ACC is worth the $2K option price, and for my driving it really isn't unless it somehow enhances the collision system to avoid a crash.

nyca

OK, so below is the description from the Porsche website. First phase is the alert and the chime, second phase is the jolt people describe above. Next phase is either braking step-up in reaction to the driver braking, and lastly it applies the brakes itself - but the way it reads is that it will only slow the car down to lessen the impact but not stop in time to avoid the crash. ACC of course will stop the car, but it's not clear if there is some failsafe mode for ACC that uses the radar to stop the car even when ACC is turned off.

The standard camera-supported Warn and Brake Assist significantly reduces the risk of collisions with vehicles, pedestrians and cyclists. In the first instance, the system warns the driver visually and acoustically. A braking jolt follows in the second phase if there is greater danger. If the driver then brakes, this is intensified to full braking if necessary. If the driver does not react, automatic emergency braking is initiated to mitigate the consequences of a collision.

kim9701

My understanding is that ACC is for cruise control where the car will automatically keep a set distance from the car in front with various speed. But, for auto emergency braking, that feature is standard.

dmacker

I was a few sessions into an HPDE track day when on one of the laps I got the chime and warning symbol.... me and my instructor just looked at each other like "what the..."

I took it as I wasn't pushing hard enough on the previous laps, lol.

Radiationman

ACC as in Adaptive Cruise Control? That shouldn't be the same as the collision avoidance/emergency breaking function being discussed. There's an overarching question if you need ACC for the full breaking to occur with the collision avoidance, you probably don't looking at the responses but I'm pretty sure that none of us are brave enough to try and deliberately trigger the breaking... Maybe we can dare a dealership to do it for us with one of their cars

As for whether or not ACC is worth $2k - if you're going to road trip the car with cruise control, I'd say yes. After having done several long trips in an Audi and Mercedes with their version of ACC - it's definitely worth it, especially in highway construction zones where the cars in front of you may randomly speed up and slow down for no reason. ACC will maintain separation as the speeds yo yo around.

nyca

Oh of course, its Porsche that should be producing some videos of how it works. Yes, in an everyday car, ACC is convenient. But what I am saying is, that in a sports car where the ACC is less likely to be engaged, the feature only pays (to me) if it enhances the collision avoidance system somehow (all the time, not just when its switched on). And I can't find any evidence that such is true.

drcollie

Who's going to take one for the team and see if the car really DOES stop if you don't brake in time?

Shogunade

HA! Idk about this car yet, but in my DD its a love hate relationship. There's numerous times when the collision brake will activate, harshly, and everyone in the car is freaked out. Just glad there were never any tailgaters. It has saved me though once while backing up and I know if it weren't for its intervention, it would've been an expensive day. So, it's a double edged sword. At the end of the day I'd rather not have this feature. The tech isnt 100% yet. Ask all these Tesla people whose cars have been recalled because of rogue auto drive.