There is no brake involved with cruise control. What you are describing is bad drivers who do not use cruise control. It's actually extremely pleasant and predictable to be following a driver who is using cruise control. Following a well-regulated self-driving car would be similar.

My car has cruise control with brake functionality. Not sure if I've ever seen it actually do it - I only really use cruise control on the motorway, where I expect wind resistance is a major factor - but apparently it will apply the brakes to maintain the set speed when necessary.

At town speeds I would expect it to use the brakes a lot more readily. At 30mph in 3rd (2000rpm) or 4th (1500rpm) there's not really all that much engine braking, and wind resistance won't slow it much either.

(Mine is a 2010 model, but I think this stuff was introduced in 2004-6, something like that... it's not exactly new technology.)

My car has a CVT (Continuously Variable Transmission). With cruise control enabled, going downhill, it will actually change the effective gear ratio and "downshift" automatically.

(Once or twice when going downhill without cruise control, just using the brake pedal, it "downshifted" automatically while I had the brake pedal pressed.

CVTs are computer controled and better than manual/standard for gas mileage, but with the downaide that you can't tow heavy loads.)

> but with the downaide that you can't tow heavy loads.)

And the frustrating rubber-banding.

I've never heard of that phrase before, so I went to look it up. Apparently it has different meanings to different people when it comes to CVTs. I haven't experienced any of those different issues.

When it comes to accelerating and high RPM, I just don't mash the gas pedal down. By pressing the gas pedal on my car just enough, I can accelerate past other cars without high RPM just fine.

Gas pedal management is definately different with CVTs and other types of transmissions if you want a good driving experience.

My car absolutely uses the break when required to maintain the set cruise control speed, I've watched it happen. The car I owned before my current car didn't use the break to keep to the set cruise control speed though, so I get why you may think there is no break involved. It largely seems to depend on make and cost of the car you're driving.

Our Passat uses brakes for cruise control, our older Kia Ceed did not. I actually hate when it uses the brake. The non-brake method is much better imo. Feels like such a waste to heat the brakes on a steep incline instead of just rolling with it.

I'd have said age and which assistance systems there are. In many older cars there's just no path for the CC to control the brakes.

Yeah true. Seems like the more feature complete assistance systems are making their way down to even some of the more low-end brands these days. Level 1 autonomy is getting pretty old hat now I guess.

All SDVs that I know of operate some kind of longitudinal controller that has access to throttle and brakes at a minimum. That and steering wheel angle (or torque, depending) are the two essential control primitives. All the motion planning stuff happens on top of this.