Adaptive Cruise Control a bit violent on brand new MY22

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Active member
Oct 20, 2017
I just got a brand new MY22 leaf, 40kWh with N-Connecta trim (so it has adaptive cruise control and a navigation system, but not pro pilot).

As the title says, I find the ACC a little violent. I'm using it in city stop-and-go traffic, but it has a tendency to sort-of not realise the car in front is stopping, and then realize late and brake rather abruptly. When accelerating back up, it likewise tends to accelerate harder than I normally would. Perhaps some part of this is psychological - I'm seeing the car in front slow for a roundabout or a stop sign, I'm seeing the brake lights illuminate, so I know a stop is coming... but all the car can "see" is the radar distance between me and the car in front, so logically speaking its reaction will always be a little delayed compared to mine.

I reckon this is normal behaviour since the one I test-drove before buying my leaf was somewhat similar, but has anyone found a way to tame it a bit? I'm just curious why it tends to be so violent. It feels like it's braking hard at the last second instead of smoothly coming to a stop. Admittedly stop-and-go traffic in Malta can be quite challenging, one moment you're doing 60km/h, next moment you have to stop dead due to traffic.

I've found that it's worse (i.e. more violent) if you set the spacing (i.e. car-following distance) to be closer (1 or 2 bars instead of the default 3 bars), and found that it improves slightly if you set a target speed close to what the traffic is actually doing. For instance if traffic is at 30km/h, I get better behaviour out of it if I set the cruise control target to 30km/h than if I set it to 60km/h (though the ultimate result is fundamentally the same because obviously it tracks the speed of the car in front).


P.S. on an unrelated note, has anyone figured out how the brake pedal works? A hydraulic diagram would be awesome. I perceive it blends regen with mechanical braking, but oddly the pedal doesn't really get stiffer as you brake harder, in fact I can easily push it all the way to the floor with the same pressure I use for normal braking, and it was the same in the test drive model, so it's something intrinsic by design. It feels more like "brake by wire" than a direct connection to the calipers. I'd really like to understand the underlying mechanism. If I catch it at the right moment, I can even feel the pedal changing stiffness as I engage or disengage e-pedal mode.
The first time I drove my '18 SL (home from the dealership) I had the same reaction - horror. You basically have to do the braking when the car ahead is more than a few car lengths ahead. I actually find the acceleration a little weak, though, so I suspect it is, as you speculated, a psychological thing. And when I drove my '21 home last year, I thought the brakes had glaze on the pads, they were so weak. They still are, but I've adjusted.
Most experienced drivers usually scan the road ahead and know when a hard brake is coming up and act accordingly. This is where all ACC is falling short as they have no way of "knowing" whats going on couple cars up the road ahead of them. Focusing on just the car ahead of you is a recipe for disaster especially on roads with higher speed and less tolerance from other drivers for safety gaps in between vehicles.

And yes I have had to take over from ACC couple times already to avoid unpleasant interactions with my insurance company... Still, it reduces a lot of driver fatigue by taking care of 80% (imho) of mundane driving activity.
I find the ACC in my Leaf to be much smoother and more consistent than in the various ICE cars I have rented with the feature. But as oldmancan said, you still have to pay attention.
Regarding acceleration, I tend to accelerate gently, the ACC tends to accelerate what I would call "firmly". I think part of the feeling is also psychological, because the car is accelerating without your control so it feels stronger than it actually is. I had this experience back when I drove an Alfa MiTo - when I floored it as the driver the full-throttle acceleration was fun and "just enough", but when I was a passenger in the front seat and my friend floored the same car, the acceleration was terrifying and it felt twice as fast. And with the exact same car, when I was a back-seat passenger, the road bumps felt much more severe than in the front.

In short, I noticed a significant correlation between my perception of speed, and the level of control I had over the vehicle (which explains why my passengers tended to feel uncomfortable at speeds that were nothing special to me). I'm sure that's part of the reason for what ACC feels like.

I will be observing it more closely on the next few drives to see how well it reacts to the distance to the car in front. I found that if traffic stops, the ACC disconnects after a few seconds of standing still. This is fine in e-pedal mode because the Leaf then just stands still until I press the gas... but with e-pedal disconnected, once the ACC disconnects due to a short period of standing still, the car resumes its normal behaviour of creeping forward slowly. I haven't had the courage to test whether it will actually slam into the car in front of me in that situation, but it seems that it will. I know there's a loud beep when ACC disconnects, but it seems this is a bit of an oversight in the software. Seems it would've been safer to just have ACC stay on even when traffic is stationary, and to move off normally once traffic starts moving again.

I know they probably did that because inattentive drivers could potentially forget the car is in ACC and exit the vehicle while it's stationary (with ACC still on), but they have the door sensor and seatbelt sensor (and I think even a seat weight sensor) that can force the car in Park gear if the driver tries to exit - so I can't think of a legitimately good reason for ACC to disconnect when the car stops for more than a few seconds.
Probably not relevant to this thread talking about ACC but I also don't like how regular CC tends to "floor" the car when going up a hill, it drives me crazy. I also don't like how it acts when coming to the crest of a hill, again it goes faster than I would and it's a bit unnerving as I like to know what's over the hill and the car doesn't. I don't have ACC and can't believe I'd really like it, whenever other people drive I generally feel they are going too fast and tend to wait too long before braking, must be a control thing :) The only time I really use CC is on a generally flat straight road where I'll be driving for many miles, otherwise, in the city or on curvy hilly roads I like the feeling of actually controlling the accelerator myself. I've never driven in a car with any sort of "auto-pilot" but I'd think I might be terrified and would quickly turn it off. I'm not sure I even like the idea of other people using it but seeing how some people on the road drive themselves, maybe pro-pilot would be an improvement :D