an event happened in our session yesterday that raised a question we couldn't find an answer to.

to let you know the brief situation, the party was traveling on foot down a road, when a landspeeder zoomed past, a man on the back firing a repeating heavy rifle mounted on a turret. we applied due to the size difference, but the question was raised about speed. we had black against due to them moving, but do they have a penality due to their speed? what are the rules for speed differenece with ship vs. people?