The vehicle rules in Savage Worlds are Fast! Furous! Fun! I have a little bit here to clarify things, but there isn't much to do with them, really. Look for new designs on this page at some future date!
Clarification
Two weapons that share the same facing, are fixed, and are fired together, are treated as a single weapon with an RoF equal to the sum of the individual weapon RoF's.
House Rule
A pilot of a vehicle with fixed, forward-firing weapons attacks with the lowest of his Pilot and Shooting skill. This does not apply to any passengers or to vehicles with weapons mounted on pintles or turrets.
In the case of a land- or water-based vehicle, substitute Driving or Boating for Pilot.
All other modifiers apply as normal.