After driving HGV for 35+years There are only 2 killers within the Cabin of a car +lorry the heater & the driver, the driver controls the heater, radio, the mobile, the Machine will only do what the driver controls it to do. T.W.R
Drugs and tireness must surly be the greatest causes of not only bad concentration but also of bad driving! Although some people can be fully alert and still drive badly.
I've recently purchased a Ford Focus C Max with tinted windows and I must admit they have made me more aware of what is around me, as a quick glance over your shoulder isn't enough. The best bit about them is that I am no longer blinded by some idiot behind me on full beam.