Both have a very simple there/not their car silhouette to let you know if it detects the car in front of you. Just below that they also have some sort of colored to tell you how close the car is (good, clothes, to close). Last is a silhouette of your car. All three in a simple stack.

It’s an excellent design, perfectly glanceable. I did rent a car once that showed you how many feet away the car in front of you was. It was kind of interesting but I found it completely useless.

Realistically when the car in front of you starts getting close enough that the indicator changes, the car is already slowly slowing down. If it turns red, your car is slowing down faster.

You really don’t need any of the numbers, and they would likely take longer for a person to process than the simple visual imagery does.

I haven’t had an issue of not understanding what the car is/is going to do. The only real prop I’ve experienced is some cars are willing to accelerate/decelerate much faster than I want them to, largely for comfort reasons.