This system applies to moving people just as much as moving cars. But for political reasons it makes sense to emphasize the extent to which this is about car owners.
also what about safety? If there is an accident then you will have a huge pile of cars/sleds crashing into each other; How do you get injured out of a narrow tunnel? What about fires? What about ventilation (in case of fire) ? These are all problems of tunnels, now the narrow tunnel makes these problems more difficult to deal with.
Depends what his goal is. Currently getting from A to B in a car at a certain time involves traffic jams.
If his goal is to get from A to B most efficiently in a car then it's one of the best ideas.
If his goal is get people from A to B via any mode of transport, perhaps trains. But he owns a car company, so that's not exactly in his interest.
Also with cars it's truly A to B. Not A to subway/carpark, wait, travel, walk to B.