[NeilBlanchard]

Driving such a machine would be a massive problem on narrow roads, with other cars in adjacent lanes, etc. On my xA for example which is ~13 feet long and ~6 feet wide, then a 30 degree swing in either direction would be making the total width well in excess of 10 feet! (I drafted this in DataCAD to check...)

Such a system would have to be automatic, because the driver already has to think about enough, and could not manage very well, if not actually harm the efficiency?

If it was automatic, then the driver would not know from one moment to the next how wide their own vehicle would be! And, the computer controls, sensors, adjustment mechanisms, and the power use of these, etc., would make it tough to justify, IMO.

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OTOH, I think that similar to what Citroën has done, I think that an integrated ride height and leveling suspension would be feasible and beneficial to the aerodynamics of the body. I also think that such a system could be used to (re)generate some electrical power, to remove the need for an alternator, as well. I'm trying to work out whether an air or electrical or hydraulic suspension system would be the best way to go. (Remembering too, that I would also like to have non-inflating tires and rigid wheels that yield as low rolling resistance as possible.)