ArieAvnur

I just discovered a hazard with the 450h cruise control: When the dynamic cruise control or radar control is on and detecting short distance to the car ahead, and I raise the cruise control lever to increase speed not aware of the short distance, the system "collects" the repeating "raise" command but does not respond. This causes me to continue and hold the lever up and that sets a very high set point. Once the car ahead is gone, the system accelerates to this high speed, that could be very high. I consider that a safety design flaw. If the system can't raise the speed it should: (a) not raise the set point, (b) give some audio feedback that the system can't respond to the command. Raising the set point without feedback like the actual speed is dangerous.
What do you think?

LordBowral

Its shows you on the dash the set speed increasing as you hold or tap up the lever ... its not hard to use once you see the number

RXOwner

It expects the driver to think.

Vincent05

Yea lol. Who in their right mind would increase speed when there's a car in front of them? Unless they are looking to ram someone from behind.

RXOwner

I am saying that it is your responsibility to take over and over ride the system. Under these conditions I would have already disengaged the system.

yardie876

Also, this isn't a Veyron. It isn't going to downshift into second and shoot up to the set speed in 2 seconds. The driver has plenty of time to make adjustments to the set speed.

Vincent05

Oh, I agree with you. I don't use cruise control unless the car in front is atleast 1/4 mile away.

unowned

I disagree with the OP. I set the max speed I want to travel at and let it do it's job

DunWkg

Vincent05,
There must be no traffic on your roads. Isn't 1/4 mile about the length of 4 football fields?

Someone correct me, but aren't the settings on dynamic cruise 160 feet, 130 feet and 100 feet? A 1/4 mile is about 1,320 feet. Dynamic cruise is not going to work for you.


ArieAvnur,
Yes, I agree, when first using dynamic cruise its easy to set an excessive speed, if you're not glancing at the multi-informational display. I know I said, "woow baby" as the car sped off with the cruise set at ninety when changing lanes after following a semi doing sixty.

I just bump the lever up to get one mile an hour increases till I get the speed I want, say 75 mph and go merrily down the road. And remember to turn it off when pulling off the road onto an exit ramp.

Vincent05

Oh I meant the standard cruise control. Was never comfortable using it with alot of traffic. That is why I only use it when there's no car in front near by. Still waiting for a better deal to pick up my RX then I'll test out the dynamic cc.

jackgong

anybody know are the eco, normal, or sport mode still effective under the radar cruise control?

techgirl

I noticed the same thing with the dynamic/adaptive cruise control when I picked up the car yesterday. Increased the set speed, but the system kept following at the same distance and did not accelerate (I thought that I was further away from the vehicle ahead than the system did) - the graphic display did show what the new set speed was. At first, I was a little annoyed and thought that something was wrong with it, but then realized that the system was doing its job and keeping the distance fairly constant based on what the driver in front of me was doing. Historically, I've rarely used cruise control due to the amount of traffic and number of aggressive drivers in the Northeast. Dynamic/adaptive cruise control may change that.

At face value, I wouldn't think that eco, normal or sport would make much difference in cruise control as the radar system should prioritize safe following distance over acceleration.

GSY

I had the exact same experience as the OP the first time I used the system. He's right - it is an error in design. Once that happened I learned to read the cruise speed on information display and it work great but it only takes one error for an accident.

SW17LS

I don't mean to be snarky, but when the set speed is displayed on the instrument cluster how is that an "error in design"? You set the speed you want and it tells you what speed you've set. If it says 95 Mph...that may be higher than you want.

I don't have a 4RX but I've had multiple vehicles with radar cruise now and they all operate this way. Set the speed you want, and it negotiates to that speed when conditions allow. That's the whole point of the system.

And how can you not realize there's a short distance to the vehicle in front of you? The system doesn't turn off the windshield.

And to the folks who say they would deactivate it when cars are around. Why?!? That's the entire point of radar cruise control.

Baffled all around

LordBowral

Don't worry ... They are also hard at work trying to figure out how to turn the Nav screen off, cause they don't need that either and it distracts them ! Lol