@arstechnica saying we need x or y while suggesting the set of solutions includes cars suggests what we really need is not going to happen. Unfortunately that seems to be what is happening, we keep raising the bar, not realizing we need to start lowering it to get anywhere. It comes down to energy used per passenger mile. This is all well understood. A 2 to 5 ton rolling brick of batteries does slightly drop CO2 per mile but can't scale like mas transit.