Unless your friend's boss is paying his salary while he's commuting (IOW, he's "on the clock" while commuting and gets to spend less time in the office during the day as a result of working while commuting), it's unreasonable and, as you say, unpaid work.
His boss has explicitly stated that the commute time is not "working" hours, so it absolutely would be unpaid work, unless he's going to change that rule if your friend is doing this "planning and communicating" while he's commuting.
Your friend's commuting time is his time to use as he sees fit. If he's driving his own car, he should be driving, not doing work.
Are his teammates even available during this commute time? If they're commuting as well, and he's expected to be "communicating" with them, they probably aren't available either. If they're not in the office, then he'll be imposing on their non-working time.
This is an unreasonable request IMHO. The appropriate response is "due to the nature of my commute, it's not safe, reasonable or possible to engage in those activities during that time."
Addition based on comment
If your friend is expected to work during his commute, then his boss should:
- Pay for the commute costs
- Allow for fewer hours in the office (since he's working during the commute - otherwise he's working more hours each day, for the same salary)
If your friend won't speak up for himself, no one else will.