[Vince]

pawn Код:

for(new i, vehicleid; i < MAX_PLAYERS; i++)
{
    if((vehicleid = GetPlayerVehicleID(i))) // Note: we want this assignment, so one '=' only.
    {
        new Float:vhp;
        GetVehicleHealth(vehicleid, vhp);

        if(vhp < 250.0)
        {
            SetVehicleHealth(vehicleid, 250.0);
        }
    }
}

Put that in a repeating global timer.