It does target vehicles too, but only if no infantry unit is in range.
It's an anti infantry unit though... As u can see in "Arsenal".
Even if there's no infantry in range, the damage it'll do to vehicles is minimum (4 times less effective then vs. infantry)... And vehicles usually are thicker (more resistant).
My advice: research the cobra (anti vehicle) and then the upgrade (cobra shield) as fast as u can... never mind the next base or whatever other research unit u have in mind.
Once u have the cobra upgrade, replace all your venoms with cobras. There's no such thing as too many cobras (or Salas later on) :)
(U can keep some venom, but protect it with cobras... watch out for the rt)
