Natural gas car not useful
Basic decision against gas cars. Why this dispensable step in direction of a future mobility is not necessary.
At the Citroen C3 is the difference between gasoline and natural gas 154 g CO2/km and 119g CO2/km. The bigger C4 emits as a hybrid only 90g CO2/km and even this can be radically reduced changing the monovalent Dieselhybrid to a bivalend Hybrid where it's possible to drive the first kms by electric power, falling down from the sky.
Why all this effort to reduce the CO2 emission from the small C3 from 154 to 119g/km, when the bigger C4 shines with 90g/km. It's only 35g less CO2. Instead of a costly gas refuel station in the garage, spent a electric charger for the C4. When a C4 drives 39% of his ways by electric power produced withoug CO2, this would be also 35g less CO2. Down from 90g to 55g.
More than 60% efficiency at electricity from biogas is state of the art. But what is the efficiency of a gas engine in a car? Not the best efficiency, but the average efficiency in city traffic, because the gas is not for long distances, the C3 drives on long distances with gasoline.
It could be a 1:4 difference between biogas in a high temperature fuel cell with steam turbine to make electric power also from the waste heat and a high efficient electric car and a gas car with Otto engine.
Out of this reason, use resources usefull, make out of gas or biogas electric power in a high efficient fuel cell and recharge a bivalent hybrid car instead of wasting it in very inefficient cars with Otto engine in city traffic.