Sad to hear this but it is typical press getting it half right.
The bonnet vents would not put fumes in to the car surely. I can see the fumes coming in through the AIR vents inside the car but unless the exhaust was somehow leaking in the engine bay then how would the polluted air get in to the air intake.
The air intake is behind a bulkhead, if the fumes were comoing out the exhaust then they would find there way in anyway. The problem was surely that 1) it had no cat and 2) that they were sat at idle and somehow the dangerous exhaust gasses had somehow got in to the air intake.