About humans and carsCars are the most liked enemy of environment protectros. But nevertheless is nearly nobody willing to renounce. For luck, this is not necessary. It depends only to choose the right car..
The most important criteria is the demand for yielding ground area to produce the energy to drive. Most surprising, a car needs less yielding ground area than a human.
The ground area for bio fuel looks first bearable, but only valuable farm land is suitable for this. This makes the area demand 10 times worse than on the first look.
The low efficiency of electric power to hydrogen and hydrogen to propulsion power worsens the performance of photovoltaic. Photovoltaic is far more efficient than plants. Only a nearly direct connection to the electric engines shows the full superiority of photovoltaic against plants.
How silent would be our towns, when the main streets would be below earth? In this question is "would", because it is just right now impossible.
Even when the exhaust gases are detoxicate by a catalytic converter or only water damp at bruning hydrogen, there is a huge amount of air in the tunnel to be exchanged by fresh air to avoid a CO2 intoxication or in the most harmless case at hydrogen, the tunnel looks like a damp bath.
A car with ICE internal combustion engine needs about 100 times more fresh air than a human. This makes airing a tunnel used by ICE cars very expensive. Much electric power for the fans and the air has to be brought in the free.
Attention! Biomass 1:10 to good assumend