Re: If you are going to describe a future, make it aspirational.
"Solar cells on a car roof will make no significant contribution to the power. Physics is against you here. Wrong inclination, for a start. Plus you've got the extra weight to haul around. Far more efficient to put them beside the road."
I accept that in terms of current production technology. But then there's this on the horizon or any one of a number of current research avenues as well as others we've not thought of yet.
The problem with fixed power generation is getting the power to a moving vehicle. Wireless power transmission is still significantly lossy and with solar PV we're already currently only at 25% efficiency. I accept that will probably improve too, as may wireless power transmission. Using a "charging car" in a "train" on the motorway might mean we need a standard mechanical method for the vehicles to connect while in the train. A standard as ubiquitous as the "fifth wheel" on lorries.
It's good to think about this stuff :-)