I talk all the time in the car, it wouldn’t be uncommon to have an hour long conversation. as a matter of fact I talk more on the phone in the car than anywhere else. I do close to a 3 hour round trip commute to work and to make the most of my time I plan all of my personal and work calls while I am driving. I do use Hands free because its more efficient and also illegal otherwise.
I don’t think it impairs my driving at All because I generally I am in traffic and have to pay close attention to the road, I not only look at the cars ahead of me but I am looking at the cars ahead of them as far as I can see. I try to estimate the flow of traffic and use my cruise control to keep me a car length for every 10 miles of speed.
The real problem with talking on a phone while driving is it impairs the already incredibly poor driving skills and manners the majority of people have on the road. It seems everyone driving only looks at the car ahead of them and not all the traffic around them. Its amazing the number of people I see trying to do 70+ miles an hour in 50 mile an hour traffic. doesn’t matter which lane I am in I can guarantee I’ll be tailgated by someone usually Chevy pickup that wants to do 80. he eventually passes and flips me the bird . In most cases the way traffic is I end up passing the guy/gal and give them a nice wave.
In general if you concentrate on your driving I don’t think talking on the phone is any different than talking to a passenger.