[trhway]

that is a fallacy. Passenger vehicles are responsible for 10% of global emissions - so whether to drop it 4x (100mpg instead of 25mpg) to 2.5% or drop it to 0% wouldn't matter much. And using renewables for electricity we basically drop emissions to the rounding error around 0.

[adrianN]

Using global emissions is a neat trick here, because globally almost everyone can't afford a car.

[morsch]

Emissions will have to be reduced across all sectors, so if you merely manage to drop it to 2.5% of current emissions, that'll be a larger percentage in 2030 and 2050. If the trend continues and more people get more cars and drive them more (saving the world all the while), the share will increase further.

Of course an infinite supply of green energy would solve everything, but unfortunately that's not available. We're not supplying enough green electricity to cover current demands, much less enough to cover the roughly doubled demand if we were to shift all transportation to EVs.