Couple of items Re: diesel. One is a personal experience w/ a diesel Puegot (404??) four door I rented some years ago in France. Drove it for a few days before I even knew it was a diesel, if you can believe that. Car had wonderful driveability, was fast, and when I finally did figure it out, was impressed with the mileage efficiency. Weather was hot then, and so I had the A/C on and windows up. Very well sound-proofed chassis. Rolled the window down once inside a parking garage, and thought: gee, that engine sounds like a diesel. duh!!! [ And yes, I would have figured it out on the first stop for fuel.]
Second item: consider a barrel of oil about to be refined. Under optimum conditions, it will yield a certain percentage of gasoline and a certain percentage of diesel fuel, and a short list of other cool stuff. You can't refine the raw material into just gas or just diesel. The chemistry does not work that way. And so, all things being equal, it would make sense if all the cars and trucks in the world were made up of the same rough percentage of gas powered vs. diesel powered. That way, all of the refined material would have a place to go. I have been told that way back when the auto industry was getting started, it developed (by choice or by chance, I don't know) that Europe would have the diesels and the US would have the gas powered cars, rather than each region having to support the same ratio of both. The oil companies just did it this way. Excess refined gasoline and/or diesel fuel was, and may still be, shipped back and forth across the pond to maintain the prescribed ratio of gas cars here and diesel cars there. Boils down to basic chemistry, so I was told.