vehicle as is stated in the documentation does not work in Arma 3. the vehicle will always equal the player; however, you can get the class name of the vehicle in this manner(where _x is a player):

When I use this in my code:

if (vehicle _x != _x) then {

then it always returns false. It recognizes my player, but 'vehicle _x' returns _x always.

However if I do the following:

typeOf (vehicle _x)

and it will properly get the class name of the vehicle that the player is in. So to properly see if the player is in a vehicles you would need to do something like this(where _x is a player):

if (typeOf _x != typeOf (vehicle _x)) then {...

So either the documentation is wrong, or something is wrong with arma.
{F22747}