[Fj0rtizFredde]

You could use this function I found here at the forums

pawn Код:

IsBike(playerid,vehicleid) // Credits to the creator!
{
    #define MAX_BIKEZ 13

    new IsBikeA[MAX_BIKEZ] =
    {
        581,523,462,521,463,522,461,448,468,586
    };

    vehicleid = GetPlayerVehicleID(playerid);

    if(IsPlayerInVehicle(playerid,vehicleid))
    {
        for(new i = 0; i < MAX_BIKEZ; i++)
        {
            if(GetVehicleModel(vehicleid) == IsBikeA[i])
            {
                return true;
            }
        }
    }
    return false;
}

Then you could use it like:

pawn Код:

public OnPlayerEnterVehicle(playerid, vehicleid, ispassenger)
{    
    if(!IsBike(playerid,vehicleid))    
    {        
        SendClientMessage(playerid,WHITE,"You have entered a car");        
    }    
    return 1;
}