You should discuss it from the principle of combustion. In addition to filtering the dust in the air, the filter also has an adverse effect on the intake effect of the engine. In order to save fuel, we must find ways to reduce the heat dissipation of the engine, because the heat dissipation of the engine will consume 50% of the combustion energy!
Forget it, that thing won't save fuel. This is the same as adding a magnet to the oil pipe a few years ago, but it will make the engine work better. Saving fuel is sheer nonsense!