Don't be surprised at the use of the plural here. I'm talking about two different people displaying the same behaviour and sharing other characteristics. However, each time only one of them is present - so we are alone in that car.
My front passengers are closely related to me, and much older. They got their driver's licenses before I was even born, so they are much more experienced. I got it a few years ago, and I know the rules better than them. But they are careful drivers and are never involved in accidents.
I also drive carefully, trying to minimize risks - neither driving riskily (too fast), nor inducing risky behaviour in others (driving too slow), but in accordance with the situation and the rules. Imagine me as someone who just got his driver's license and still follows all rules (and knows them by heart), but with more experience and routine. For sure, I do still lack experience and so I dislike distractions.
My front passengers do not fully trust me yet or try to show off their greater knowledge and routine. I am more than glad if people give me helpful advice, but this is not what this question is about.
When I'm the driver, they sometimes start to meddle with my driving, e. g. start pointless discussions about what rule I just violated or which turn I should take - reminder: That's when I am right! They already even tried to fumble with the appliances around the driver's seat.
A more specific instance: I'm taking my close elder relative, "Mallory", somewhere. After driving for some time, a conversation like this ensues
Mallory: You didn't need to blink.
Me: I did.
Mallory: No, not on this kind of road.
Me: (wondering about that totally strange suggestion)
Mallory: I got my driver's license before you were even born. On such roads ... bizarre explanation follows
Me: Could we discuss this later?
Mallory: Didn't hear what I was saying. You understand?
Me: Mallory, please stop it. You are distracting me.
Mallory, after some attempts, allowed that discussion to die down. At our destination, she was proven wrong.
This is just one example of such pointless discussions people try to draw me into. I'm a bit afraid of them, as driving a car demands a lot of concentration on my part. Yet, they seem to take my (relative) inexperience only as a means to score a point in some discussion.
Such pointless discussions are annoying and distracting, even if they are shorter. Even if Mallory had been correct, there was no point in discussing it at that very moment.
Now, this is a real distraction for me. I want to concentrate on driving the car and safely bring us to our destination. Pointless discussions don't drive us forward.
What are effective ways to deal with a front passenger, who distracts and annoys you?
I hope for experiences preferably polite ways to shut them down. So maybe think of family members, partners, good friends etc. on the front passenger's seat. I don't want to throw them out of the car!