This morning I was going along in typical N. California rush hour (more like 3 hours) traffic when the traffic in front of me suddenly stopped. I was going about 50 MPH. I pushed on the brake and started to slow, still with plenty of time to stop. Then my car really started to slow, like from 40 to 5 MPH in about a second. The strange thing is I didn't think I was putting that much pressure on the brake pedal or increasing the pressure. I'm not complaining as it was actually a nice secure feeling. Just curious as to what this was helping me stop.... Brake Assist? Preview Braking? Steroids?

 

Steroids..... and lots of them.

 

Brake Assist...it senses emergency braking from the way you apply the brakes and applies full pressure to help reduce your stopping distance.

 

If you apply a brake for more than a few seconds the auto tranny will downshift a gear or two as needed. I experience it all the time especially when going downhill, but sometimes on leveled roads as well. The brake assist would kick in if you really SLAMMED on your brakes. Otherwise, I'd say it was the tranny downshifting.

 

^^ downshifting wouldn't slow the car by 35mph that quickly and he would have heard the engine hitting the red line.

 

sometimes when i have the car in DS (without really knowing it was in it) the downshift when letting off the gas/braking will really startle me. It'll feel like it's stopping really fast, though it's not.

 

Gotta love that brake assist.. we had that on our FX before as well, its a nice feature

 

I love this feature on our G's....i love the back pressure of the exhaust note on the downshift.

 

I'd go with Brake Assist - although you may not have jammed on the brakes, my guess is that when traffic stopped in front of you, you stepped down pretty hard. Brake Assist has done that for me a couple of times - damn the G has some brakes!

 

My brakes have performed flawlessly and I have experienced the same thing in an emergency situation and those brakes were absolutely fantastic . I was impressed..........and safe

 

How far away were the cars in front of you? Since you have tech package it sounds like Preview Braking kicked in as well when it may have detected a car in front of your.

 

I'd guess 8 car lengths. I don't think it was just due to down shifting because I felt the brake pedal stiffen and even though I did not feel I was pushing any harder, the sensation was almost like the pedal was pushing back (harder) against my foot.

 

My tranny downshifts all the time and never did it hit the redline. It just takes a gear down. Brake assist will only kick if an emergency brake is detected such as when the wheels lock (i.e. slamming on the brake). Merely stepping on the brake to slow down will not engage the brake assist system. What the brake assist system does is detect an emergency stopping situation and apply extra full force ON TOP of the already high pressure in the brake lines. In short, he would have needed to literally stand on this brakes in order for the brake assist to kick in. Another thing with regards to brake assist: it kicks in instantaneously it doesn't wait a few seconds. From the driver's standpoint, all he does is slamming on the brakes and the car "magically" stops! Brake assist kicks in as soon as you step on the brake - you won't feel a change in the braking force from one second to another. All you'll experience is one quick stop. And finally, if he would have slammed on the brakes hard enough to the point his brake assist system engaged, he wouldn't have ended at a 5mph crawl - he would have ended stopped.

Between him stepping on the brakes and the tranny's downshift, the car can certainly lose speed rapidly.

 

Were you in D, DS, or M?

 

'D'