Q:

What is the use of か in 売り始めるか〜

I was reading an article and I came across this sentence:

車の会社がいつごろこのような自動運転の車を売り始めるか予想しました

What exactly does the か in this sentence/what is the meaning? 

A:

This か is the same as the particle we see all the time at the end of an interrogative sentence. It's also used in a noun clause like so:

いつ車を売りますか? When do they sell the cars?
  いつ車を売るか (noun clause) when they sell the cars
今日は日曜日ですか? Is it Sunday today?
  今日は日曜日か (noun clause) whether it is Sunday today

Therefore, "車の会社がいつごろこのような自動運転の車を売り始めるか" is a long noun clause which means "when the automobile companies begin to sell those self-driving cars."
EDIT:
I found a related question with an extensive answer:
Usage of か after a clause?

