There seems to be another point in the article but not emphasized: The potential role of direct fuel injection. So, go ahead and let the compression ratio go u

There seems to be another point in the article but not emphasized: The potential role of direct fuel injection. So, go ahead and let the compression ratio go up through the roof, from the piston in the cylinder and/or the supercharger. And, don't bother working hard to cool the compressed air before letting it past the cylinder intake valve. Why cool in the past? Because otherwise the heat of compression would cause pre-ignition. What's different with direct fuel injection? The fuel is not in the hot air in time for pre-ignition. So, basically have a Diesel situation and, indeed, might not need a spark plug! I'm not sure people are taking advantage of this possibility now, but have to suspect that there is an opportunity here.