The government has with taxes throughout time controlled how we power vehicles, the steam wagon's demise was due to weight and taxes based on weight, and the lean burn petrol engine again due to governments and the catalytic converter which would not work with a lean burn engine.
I have worked on two stoke diesel engines and the delta diesel was a real game changer, as was the smaller commer,
and there have been through the ages some cracking engines, but we did have some small petrol engines too, the Beford RL had a petrol as did the old Mack we had when I was an apprentice, I remember the Mack did 4 MPG light running and 2 MPG ploughing, it pushed a 12 foot V blade snow plough.
And this has always been the problem with petrol the compression ratio of 9:1 does not give the volumetric efficiency advantage of the 22:1 diesel, so we had to use diesel to conserve fuel use, however with direct fuel injection the problem with pre ignition goes, and with the Simms injection pump with the early Bedford TK multi fuel engine we could use more volatile fuels, we also saw tractors with tractor vaporising oil (TVO) or paraffin 28 sec gas oil.
The start on one fuel switch to another while hot has been done with ships for a long time, where 300 RPM was considered as high speed, 160 RPM more normal, and with modern cars if government kept their fingers out I am sure other fuels be it gas or 28 sec gas oil could be used, but the government with their rules steer the industry so innovation is suppressed, the ****el engine for example.
https://upload.wikimedia.org/wikipe...m.svg/241px-****el_engine_diagram.svg.pngthis was not the only rotary engine, but to develop them and during the development stage keep within the strict emission rules means it will not happen.
The main problem with cars today is weight, a Morris Minor weighed 775 kg and a Vauxhall Agila 990 kg mainly due to the protection measures added, but still permitted to drive a motor cycle with no crumple zones, it has gone daft. Again government intervention.
So we have the electric cars - dubbed “voiturettes” in France - are small electric vehicles that can be driven legally without a full driver's licence, by anyone aged 14 or over. ... The electric vehicles are not allowed on motorways, are limited to 45kph, and are 3 metres in length and 1.5 metres in width. If the same was allowed as a petrol car then likely would be looking at well over 100 MPG. And due to petrol being lighter than a battery the motor can have a lower output and same performance.
It is nothing to do with the fuel, it is all to do with government interference. Sorry it seems the forum will not allow me to name the engine or show the picture, we also have forum intervention.