Also, most roads are out of WiFi connectivity anyway.
I think you're totally out of touch with what the technology is capable of. After you have logged the trip, you will be within WiFi range at your destination or at other points in time.
Also, it's up to the vehicle to distill that information, so they aren't necessarily uploading Gigabytes.
Even if they were, it's quite doable.
It's also quite possible analysis of the data may be distributed, and different vehicles could share that data with each other, and once many vehicles have the data, they would start seeding the same Torrent.