Make a hybrid 205 Peugeot (petrol / electric)

[I Citro]

And if not the methane / petrol mixture, what do you think?

That it's a baroque mix I don't see what the benefits could be (but you may have your idea), or how to mix them evenly, or how to store the methane in a reasonable volume and weight. In a fixed installation with city gas why not? On a vehicle ?????? There have to be easier, profitable leads.

CNG vehicles are dual-fuel models that work alternately with petrol or methane (CNG).
The advantage of running on methane is a reduction in pollution (particles in particular). In terms of cost, the economy is very relative, even non-existent.
There is therefore no interest in wanting to "mix the 2 fuels", because that would amount (from my point of view) to cumulating the disadvantages of the 2 fuels.

The only case where the simultaneous use of 2 fuels is "rational" concerns the fitting of LPG or CNG on diesel engines. The principle consists of starting the engine on diesel and using the latter to maintain idle speed and initiate combustion. Gaseous fuel is then used for the main combustion. The interest is twofold, gas is burned in a more suitable engine (higher compression ratio and slower rotation speed which allows the mixture a more complete combustion due to the lower rate of ignition of the gas).
Finally, the conservation of the "diesel pilot injection" makes it possible to avoid the installation of a conventional ignition (heavy modification of the engine with spark plug and its electrical system).

[moimart1]

Citro, that's exactly what inspired me, I had seen vehicles that ran on diesel and methane
And I told myself why not gasoline and methane, good now I have my answer ...

If I think about it, in the end, the only way to consume less with a petrol engine is to have an ecological driving style!