this is a Missing Power classification limitation in GURPS Spirits for the second Spirit Form
The concept of paying 1 FP per hour to "hitch a ride" with vehicles originates in the first Spirit Form from GURPS Voodoo, as specified on page 62, as well as Ghost (advantage) on page 84
http://projects.inklesspen.com/fatal-and-friends/fossilized-rappy/gurps-voodoo-the-shadow-war/ comments on the negated concept:
- Rather amusingly, this also means they can't normally ride in vehicles, but can tie their essence to one just enough to "sit" by expending a Fatigue Point per hour of travel.