The official answer according to the FMCSA and the D.O.T. is “no.” However, common practice is to allow between 50-100 lbs in the trunk or out the line sight. This is really at the discretion of your carrier, though, as they risk hefty fines and lengthy inspections for carrying anything but motor vehicles.
4 things not to do (especially for first timers) January 24, 2019
3 do’s and 3 don’ts that all car shippers need to know December 12, 2018
The 1 thing smart people do when they move November 6, 2018