[mjan22640]

I guess the cooling alone cannot reach the density (and oxygen amount) necessary for the designed power output.

Yes, they put in the energy to compress the air 'offline' and then have that free to propel the vehicle. The cooling of the charge also improves the efficiency, the useful energy output is proportional to the temperature difference before and after the combustion.

A high capacity intercooler would be an interesting experiment also in utility vehicles.