I once heard on a TV program about the history of diesel engines that a) you could adapt the principle of a diesel engine for just about any fuel and that b) the reason diesel engines run on what is now called diesel is because they can i.e. diesel is a relatively low grade petroleum product and having an engine that runs on something no one else wants is an advantage.
If the above is true (is it?), what might be the characteristics of a diesel style engine that runs on petrol/gasoline? Particularly mileage, power and emissions?
I may be wrong, but I think what the OP is trying to get at is whether or not it would be possible to design an engine that would run the same way a diesel engine does, that it use the compression to ignite the fuel rather than a spark plug.
My guess is that you could, because gasoline will ignite under compression. But I don’t know what you would gain from it if anything. It’s much easier to have a spark ignite the fuel.
The effiency could be much improved, Some at full power due to increased compression ratio, and quite a lot more at reduced power output due to reduced pumping losses. High octane is not needed, or even desireable for such an engine, so you can run the cheapest fuel available, improving the economy of operation even farther.
The problem is designing an injection pump, or direct injectors, that will survive without the lubricating properties of traditional diesel fuel. Ceramics hold some promise for this.