[boelie]

Sascha is correct check these 2 differences;

Code:

GetXYInFrontOfPlayer(playerid, &Float:x, &Float:y, Float:distance)
{
	new Float:a;
	GetPlayerPos(playerid, x, y, a);
	GetPlayerFacingAngle(playerid, a);
	if (GetPlayerVehicleID(playerid))
	{
	    GetVehicleZAngle(GetPlayerVehicleID(playerid), a);
	}
	x += (distance * floatsin(-a, degrees));
	y += (distance * floatcos(-a, degrees));
}

GetXYInFrontOfVehicle(vehicleid, &Float:x, &Float:y, Float:distance)
{
	new Float:a;
	GetVehiclePos(vehicleid,x,y,a);
	GetVehicleZAngle(vehicleid,a);

	x += (distance * floatsin(-a, degrees));
	y += (distance * floatcos(-a, degrees));
}

The part where in the angle should be checked is GetVehicleZAngle(vehicleid,a);
for the vehicle and GetPlayerFacingAngle for player.
Just try it out and you'll see