slimjimtel

Wow, sorry I ever posted this! I never wanted a debate on the technical aspects of this system.

I like it, it works for me. I drive 200 miles a day, straight highway driving. 100 miles each way. It makes my drive enjoyable.

This is a system that you have to learn to use and adapt to the changing environment on the road.

williakz

I guess I don't understand how DRCC can work for you and not for me. Don't you experience other drivers moving into the gap DRCC leaves in front of you? If and when this occurs, doesn't DRCC slow down even more, enticing and allowing even more cars to jump into the gap? If it happens to me, why doesn't it happen to you?

Did you see the video of the guy in Istanbul? I believe I counted 10 cars jumping into the gap the VW Golf's ACC produced. Three of the jumps looked to be near accidents which I believe the ACC system caused. If you or I were driving without DRCC, we would be following much closer and no "gap jumping" would occur. Am I wrong about this or have you not experienced this problem. If not, why not? Do you use DRCC only in a HOV lane like the (Audi?) reviewer I mentioned? Do you use it only in the right (slow) lane where people don't bother jumping into gaps? Please help me understand here - seriously.

williakz

Not sure I get this. So you close up the gap by overriding DRCC. OK. So then you must either maintain the DRCC override (so no longer really in cruise control mode, right?) or you must let DRCC take back control and re-establish the gap it wanted in the first place. When you do the latter, the gap jumper (or his replacement) simply makes another stab at jumping. In moderate to heavy traffic, wouldn't you be in override mode more than you'd be under DRCC control? I just do NOT understand this system and why you guys love it so...

williakz

Crunching some DRCC numbers in the 2013 LS460/LS460L owner's manual (pg. 251) :

At 50mph (= 73.3ft/sec)
Long...... (160ft) => 2.2 sec gap => 10 car lengths (LS460 is 16.7ft long)
Medium...(130ft) => 1.8 sec gap => 8 car lengths
Short......(100ft) => 1.4 sec gap => 6 car lengths

I think a 6 car-length gap at 50mph speaks for itself as far as viability in other than VERY light traffic. I saw where the Porsche system (I don't recall what year) allows selection of a 1 second gap. If Lexus allowed the same, the size of the LS460 gap at 50mph would be around 4-1/2 car lengths - still large, but 25% smaller than now and about halfway to optimum. I figure, based on my driving experience in the U.S. that a 3 car length gap (approx. 0.7 sec gap at 50mph) would generally serve to keep MOST gap jumpers at bay and would vastly increase the effectiveness of the Lexus DRCC system.

CJITTY

In light to moderate traffic, it does a great job of maintaining space but on the occassional times someone is about to sneak me from the right, I just tap on the pedal..close the gap until the threat subsides and then let off gas letting DRCC take over. I like having the system help with those sudde. Slow downs that happen, especially here in Metro Atlanta. Without radar cruise on and activated, the PCS system only works if you are for sure going to hit something. My new Dodge Durango radar is always on and warns me well ahead of time whether on DRCC mode or not. For example, if a car in front of me slams the brakes and merges over to catch a turning lane last minute, my Durango light and sound warnings to brake. .if I don't respond the system will. I would much rather have a more active nanny than what my LS600 does. I have been within a foot of hitting someone and my LS600 PCS did nothing. I assume thats by design because it determined I wasn't going to crash. I wonder if the new 2013 body style acts more like the Durango or do they still have the basic PCS and Advanced PCS to choose from. I need to research this more because my Durango DRCC and PCS system is way better. Then again, the technology is about 7 years newer than my 600

williakz

On collision avoidance, the 2013 LS460 (don't recall specifics on L or 600) had either PCS or APCS or neither to choose from. I was not interested in APCS unless and until I could give PCS a good shaking out. Having done so, I don't think I'm a good candiate for APCS as I learned to drive (so still do) somewhat closer to the limits than these systems were designed for. I hope to be dead and buried before all vehicles MUST communicate with each other and heed the electronic dictates of the International Interstate Authority.

On DRCC and the Bypass, I'd still like to see some video. If not to look for evidence of the shortcomings of DRCC, then simply to see visual proof that light-to-moderate traffic on the Bypass EVER happens! And I note once more that marketing (see videos made by local dealers of all brands on YouTube) targets ACC systems at relieving driver stress in heavy traffic situations. NOT my experience and not yours either from your response. Thanks for the conversation; these systems and the issues they present are complex and take time to work through.

Tee

Demo of how the 2013-plus ASDCC works...


Demo of how DCC works...


2013 Advanced PCS Demo


Live demo of 2013 LS Advanced PCS


2008 PCS Demo

williakz

Live Demo (Video #4) is of Advanced PCS (APCS), not PCS as titled. Video #5 is how PCS in my 2013 LS460 operates - boosts brakes, tensions seatbelts, and issues warnings (visual and audible), but NO active measures taken.

Question on All Speed DRCC vs "regular" DRCC. I've read where one of the major criticisms of ACC systems is when in distance regulation mode with a decelerating forward vehicle, the NON all-speed systems would suddenly cut out at 25mph and leave the driver to slam on the brakes to avoid a collision. All-speed was developed to avoid this system vulnerability, but the unintended consequence was that drivers and marketers began to use the systems in heavy traffic (stop-n-go) on surface roads as well as congested freeways. Make sense?

dominb

I was using it almost all the time on my way from Chicago to Yellowstone National Park, over 1300 miles one way. I felt more like passenger than like a driver

Nospinzone

The system on my 2007 does turn off under 25 MPH, but this is a zero safety issue. If I am going along in slow traffic, say at 30 MPH and traffic slows even further so that the system slows my car to 25 MPH, then there is a visible and audible alert that the system is deactivated. At that slow speed there is ample time to apply the brakes, no panic stop is required unless you are driving like CL member robert1408's grandpa - "I want to die peacefully in my sleep like Grandpa did, not screaming like the people in his car... "

Lavrishevo

iTrader: (1)

They introduced PCS in the LS430 in early 05. My 04 has the laser cruise control and it works well. I have never tested it to see how far it will slow the car but it works great on the highway. Even though my car does not have PCS / radar cruise it will apply the brakes to slow the car appropriately. Personally, I don't enjoy using the system in traffic. As others mentioned, it does leave maybe a little too much room for drivers to cut in front of you but overall I really enjoy it.

williakz

From my readings (I have full-stop ACC in my 2013 LS460), the problem is not with 30mph to 20mph traffic; there, as you say it's no problem to apply the brakes in time. The problem is 50-65mph traffic that suddenly brakes down to below 25mph. If under non-all-speed DRCC control, the system will ably brake you from 55mph, for example, all the way down to 25mph, but then it will cut you loose to deal with the remaining situation. I believe this scenario, not yours, was the one that provoked criticism of 25-and-quit ACC systems like yours and led to the deployment of "all-speed" ACC systems like mine. Ones that come with their own set of issues, as I have pointed out...

Nospinzone

Anyone who has a problem in that situation (braking from 55-65 MPH) shouldn't be allowed to have a driver's license. And trust me, they are out there.

If the system on my car detects a car that has cut in front of me and brakes aggressively, the system will also start to brake my car aggressively. About a half second later (and likely much less than that because I will have observed this maneuver) I will take over control of the braking. The below 25 MPH visual and audible warning won't even appear because I have already overridden the system.

I have on occasion saw that a slow moving car would be moving into my lane (e.g. a car entering the highway from an onramp) and overrode the system before it even had a chance to react. As others here have commented, the system is not meant to take over responsibilities the driver should be exercising.

So for that to be a problem when traveling at high speed, the driver has to be incompetent or comatose.

williakz

I don't think we're communicating effectively here.

The situation I had in mind wasn't an emergency stop from 55mph. What I meant to posit is a backup on a freeway, say near an interchange with another freeway. You're going 55mph and have been for a while, but the folks up ahead are going ZERO mph due to heavy traffic and lane changes/merges at the interchange. Your 55mph traffic is heavy as well so you really can't see what's going on up ahead. With standard ACC (like the DRCC in your car), you will automatically slow at the same rate as the car in front of you. However, during this gradual but certain deceleration from 55 to 0mph, your system will suddenly cut out from under you at 25mph. I can see how many people would consider that a problem with the DRCC system design.

Further, I can imagine that WHENEVER your DRCC begins to slow due to traffic conditions, you always have to be aware of your current speed relative to the "cut out" speed of 25mph. If the road conditions are such that speeds vary continuously between 20mph to 45mph (ie. congested freeway traffic, but not yet stop-n-go), it would appear you would not be able to use DRCC at all. Is this correct?

And finally, a general question: Why have a cruise control set speed lower limit at all? Why not accept 10mph as a legitimate set speed? Is this an historical artifact or a (now largely useless) attempt to prevent people from using CC in other than high-speed (ie. freeway driving)? Just asking...

Nospinzone

Again, people who do not have the sense to take control of their car in these situations are not competent drivers. They should wait for the google autonomous car so they can sit there and do nothing. If I am driving 55 on the highway and I see all the cars are slowing down significantly such that they will be coming to a stop, or near stop, I override the system by doing the required braking myself. A skilled driver in this situation would never be in the position to even allow the system to deactivate itself.

Correct, cruise control is not something you can use in all driving conditions, imo.

That you will have to ask Lexus. I don't know what factors they considered or what technical issues were involved.

One point, prior to radar cc the regular cc was basically unusable for me. I live in the northeast and the highways here are usually crowded. Trying to use regular cc meant continually turning it off and on or adjusting the speed, basically just a huge annoyance. Now I can get on the highway, set my speed and rarely, or never, adjust it. And when we go up to New Hampshire and Vermont I can use it on country roads where there are few traffic lights and even fewer stop signs. The trick is once I get off I89, I change the setting from 75 MPH to 35.