Impressions – ADC (ACC)
As this is a rare option on the Phaeton, I thought I should share my experiences with ADC on our car.
Firstly, I must confess that I a little bemused about the naming of the system, it is called Automatic Distance Control (ADC) when ordered and Automatic Cruise Control (ACC) in the car, for the sake of simplicity I will just called it ADC.
So, what about ADC, well I have to admit, from the first moment I tried it on a BMW 7, I knew I wanted it, it just makes the driving so much easier, and you drive differently, and I get far less tired when driving on the motorway.
The system in the Phaeton is a send generation system (ish), it is capable of retarding the car if required and can manage the car between the speeds 20mph-110 mph ().
The latest system in the Touareg and MB S-class use a higher resolution radar and can therefore take the car to a complete stop, but these have only started appearing in the last year or so. The system in the Phaeton is, in my view, far superior to the system that I tried in the BMW 7 (in 2005), as it modifies both the distance and rate of acceleration/deceleration, which I like, in the 7 the rate of acceleration was always the same, only the distance changed. For a clam ride on a quiet motorway, it is nicer if the car also accelerates less abruptly. This is also true when compared to the system in the pervious version of the S-Class Mercedes, which was often criticised for being slow in acceleration when pulling out from a car to a clear lane. But that is based on the words of others; I have not tried it myself.
When driving with the ADC, I find that you almost turn into an airline pilot more than driver of a car, you give continuous command to the car about direction, but as for management with in the traffic flow (speed and distance), the car sort all that out for you. You occasionally make a management decision to either increase or reduce the distance to the car in front or to change a lane, but that is about it. I find my self being much more aware about the cars position among other cars as I can worry less about the car in front suddenly reducing speed rapidly. You can also afford to look just a second longer at the SatNav as you know that the car is looking at the car in front for you.
I find that we also use it on normal roads (away from the motorway), but here it does not reduce the load as much and I guess that it is a more UK specific reasons for using it as it really helps in preventing me from speeding, it just manages the speed for me. As you approach a junction or roundabout where there are cars in front, it initiates the breaking procedure and I then complete it.
The biggest safety benefit I find is that it really teaches me to keep a good distance to the cars in front, in the UK traffic is much closer than say in the US or Canada, so we just drive closer to the car ahead. As the ADC system, in the Phaeton, sets the distance to the car in front based on time (the combination of speed and and distance), it ensure that the same amount of time is afforded the driver to react regardless of the speed set. Now, this freaked me out at first, as I would find that on the motorway I would sometimes keep the distance to the car ahead that equated to setting ‘1’ on the ADC at about 70mph, try setting to ‘1’ and then drive 30mph – that just feels way too close! So, I am slowly learning to keep better distance on UK motorways. If everyone had ADC, UK roads would have fewer accidents!
What are the drawbacks and problems of ADC, well there are a couple:
It uses an algorithm to make sure that it ignores parked cars and road furniture. This means that if you approach a stationary car at the back of a traffic jam or a junction, the ADC system just does not see it. This worries me less for junctions, more for motorways. However, as long as the cars ahead of you are rolling, ADC has no problem with spotting them. It even manages to see motorcycles and cyclists, which is very good, but only if they are ‘in front’ of the car.
If you are approaching a traffic jam, if the cars at the back of the queue are rolling at about 5-10mph, with you still doing 70mph+, the system will see this as an emergency, and will initiate breaking as hard as it sees fit and sound an alarm for you to take over – and this works really well, and it is a nice safety feature as I have found it spotted that the cars were really slow before I would have. So, what could have been a close call, turned into a ‘a bit harder breaking than normal’ situation.
As the manual states, the ADC system is not capable of seeing around corners to any significant degree, to ensure that the car does not run amok when you hit resume, it checks steering wheel position and if you are turning, will only accelerate very slowly until it know you are driving in an almost straight line for long enough so that it can get a view of what is ahead. I think VW has solved the problem in a really clever way, and, once you are used to it, it is easy to live with.
One more thing you notice with ADC is that it is a higher order system, i.e. it in turn relies on several complex systems to function, so to turn it on, it checks with all the other systems and needs them all to be ok before activating, it also polls the subsystems during operation to ensure that it can use the breaks when it needs them.
I so far had two occasions where the ADC fell out. First time was in the rain, the system was suddenly seeing stray radar echoes (my deduction) and turned off with a ‘Sensor Dirty’ error, this error is designed to activate with you get snow and ice build up on the front of the car in the winter, as this will obscure the sensors. The car still lets you use the ‘Cruise Control’ as if ADC was not installed on the car. Once the rain had eased, and road cleared a bit, the system happily reengaged.
The other time I suspect that there was a stray error of timeout from one of the subsystems, as the ADC system just failed as I was driving along on the motorway, on this occasion the entire ‘Cruise Control’ system when offline. I stopped a few minutes later, ‘rebooted’ the car and all was fine again, the ADC system started happily.
That is about it, if I were to buy another car, I will be looking for ADC for that car as well, I simply love it!
Modified by Realist42 at 6:54 AM 12-22-2006