Post
by SimonD » Fri Feb 04, 2011 10:24 am
[quote=""MJim""]Hi SimonD - I'm going for Active Cruise, and HUD - what were the near misses ? Was it down to people cutting in or did the system not read the traffic ahead correctly?
It's a shame the actual economy is way off the BMW figures - and quoting combined figures so far off just shouldn't be permitted. I wonder if turning the aircon off makes a big difference - although should make next to none with the weather we've been getting! I also wonder what the real CO2 numbers are!? However, thanks to these forums I'm going in with my eyes open ....[/quote]
Will probably create a separate thread for this, but here's my experience of Active Cruise .....
Generally - absolutely amazing. Only had car a month - already find it weird when driving other cars that don't have it. This will be standard on all but the most basic cars within a decade, no doubt. Makes motorway, dual-carriageway or even urban roads (works from 20mph) much more relaxing to drive - you have to concentrate a little less - but there's the danger!
The system does NOT react to stationary objects. Think about that for a minute! The electronics ignore all objects that are stationary when the radar first detects them.
It will track vehicles in front which are slowing down - and brake you down to the same speed. Even down to a complete halt. Then re-start you (if you press the accelerator pedal lightly once to confirm). This is great - and is what you need on British motorways in waves of stop-start traffic.
HOWEVER, if you come over the brow of a hill, to find a queue of stationary cars ahead, the electronics will NOT respond. No assistance, no braking. BANG!
It may even accelerate you towards the danger up to your desired speed.
On the M25 yesterday, I was in the middle lane. Way in the distance, the middle lane was coming to a halt. The car in front of me slowed. Active cruise slowed me from about 70 to about 40, responding to the car in front. Then the car in front moved into the fast lane with no obstruction, out of my way. The next car in front of me in the distance was now stationary, at the tail end of the queue. Radar ignores all objects that are stationary when it first detects them. Now, cruise control boots the throttle hard, trying to accelerate me back up to 70. HELP! .... now heading for the queue in a hurry. Had to slam on the brakes, about 2 seconds from disaster.
Second criticism. Whilst I stated in my earlier post "Active cruise applies the throttle much more gently that I can", it still does it too hard around some corners. The X5 manual states that Active Cruise consults mapping data in the Professional Nav system to determine the appropriate response to the road geography. I presumed that this meant the electronics knows the radius of curves, and calculates the maximum safe acceleration to achieve your desired velocity around bends - but this doesn't seem to be the case, or doesn't work.
Example - M11 north goes onto M25 via a sharp left hand bend with 2 lanes. I'm doing 50 following a car on the M11 with cruise set to 70. Speed restricted by the electronics. We both move left to join the M25. Car moves out of the way, or I move into the second lane (same outcome). Obstruction removed from radar's view. Active cruise boots me back to 70. Bend tightens sharply. Uphill gradient, full kickdown 3 or so gears. All of a sudden, 305 bhp is driving itself and me into trouble. Have to brake violently and disengage the system. Just didn't feel I could trust the traction control to stop me spinning even though it would. What the system should do is read the mapping data for the road ahead .... "bend tightening for the next 400 meters" - and delay acceleration until after this road section has been passed.
Overall, still mightily impressed. But it could kill you one day if you're not on the ball!
Note: New F10 5 series has an extra system which does respond to stationary traffic in the urban environment, rather like Volvo's City Safety system (seen video on YouTube).
2011 BMW X5 40d SE - Black Sapphire - Oyster - Bamboo - Active Cruise - HUD - Media Pack - Power Tail - 3 Cameras - Heated Stuff