[Chris Goodwin]

At near or point-blank:

If two vehicles are moving in the same direction and parallel, then use the faster vehicle's penalty reduced by the slower vehicle's. (In other words if the faster vehicle's penalty is -3, and the slower vehicle's is -2, there is a net -1 penalty.)

If two vehicles are moving in opposite directions and parallel, then combine their speed penalties. (For example, if both are at a -3 speed penalty, then the net is a -6.) The minimum speed penalty in this case will be -1, or -2 if the vehicles are at point-blank.

If they're moving perpendicular, toward or away, use the faster vehicle's speed penalty.

If two vehicles begin and end a phase within 1" of each other, they can each claim the point-blank combat bonus, but will still have to contend with the speed penalty.