What we know as "Cruise Control" (other terms are Tempomat, Tempostat, etc.) has been introduced by Chrysler in 1958. Mercedes-Benz was the first European manufacturer adding cruise control to a car in 1962. For years the cruise control mechanism mainly controlled the throttle. With the enhancement of modern electronics mechanical approaches to do this were replaced by sensors, electronic steering signals and computer control. And after controlling the throttle car manufacturers added the controlling of the brakes. Which makes a lot of sense, as when you go downwards it would nice to still keep the speed. In 1998 Mercedes-Benz added radar to the equation and started to measure the distance to the cars in front of the controlled car to adapt the speed based on traffic flow. These systems are called Adaptive Cruise Control (ACC). The version of Volkswagen is displayed in the picture. So, it took 30-40 years to get from throttle control to brake and throttle control and another 10 years to add traffic flow and advanced computer control. But what's next? And what is the disadvantage of ACC systems?
First, let's start with the disadvantages: ACC doesn't increase the capacity of highways and streets it actually rather decreases it. ACC tries to always keep the preset distance to the car in front of you. This leads to a lot of breaking and acceleration, which is bad for street capacity usage, but also for fuel consumption. In certain situations the systems even interpret the traffic context wrongly.
There are of course advantages too. For the driver it can be relaxing to not having to think about speed, throttle and breaking. And ACC systems can prevent accidents, as the can brake down a car completely if the driver doesn't react quickly enough himself.
But what would be the perfect solution? Imagine a traffic lane with all ACC controlled cars and computers actually talking to each other so that the car behind knows already that the car in front of him will brake before actually "seeing" it. With this you could decrease the distance between the cars and increase the capacity of the lane. For the car drivers it would almost be like riding on a train. The cars could even take over the steering, the technology is already out there.
Of course this would mean that non ACC cars could not play the same game and of course driving a car would be a lot more boring than today. Which is why I wouldn't be a fan of such a system. I actually do not really like the ACC. But cruise control clearly is a necessity today, as it's the only way to make sure you do not speed in cities and on heavily monitored highways (speed cameras).