Depends enormously on the implementation and use case. My daily driver is a Tesla Model 3, which has a big, beautiful touch screen. But I almost never touch it while I'm driving. Anything I need to control can be handled by voice command ("set temp to 70") or the scroll wheels in the steering wheel. (The one irritating exception is the windshield wipers.)

> The one irritating exception is the windshield wipers

Push the wiper button (left stalk) once, adjust with left scrollwheel (either up/down if on a recent firmware or left/right if it’s older than a year or so).

Facelift has a dedicated button on the steering wheel I think and then scroll wheel as well…

My daily driver is also a model 3 and I do sometimes interact with the screen while driving. For example if I need to see alternate routes while navigating or if I want to check my power consumption. Or if I want to listen to some Internet radio station.

I think they key though is that you're not constantly messing with the controls. It's up to you to pick the right moment and to limit your "disengagement". This is very different than e.g. texting someone while driving.

There are many things you can do in vehicles without touch screens to get distracted. You can even get distracted purely in your head while thinking about other things. Maintaining focus on what's going on while driving is on you.

I bet the overall reduced attention span due to social media and other effects has a big impact on drivers being able to maintain focus while driving.

I was annoyed that to get the safety features on the car I wanted, I had to get a configuration with a touchscreen (ironic, I know).

However, once I took it for a test drive, I was relieved to find that almost every button I want to press while driving can be found on the steering wheel without looking. Only the air con controls are left out.

I absolutely hate the Tesla screen and the entire infotainment system. I refuse to buy any car without CarPlay support.