So wouldn't it be a good middle step to initially introduce them as an addition to public transportation, specifically on rail lines? You could add a bit of sidetrack at each station where the cars would pull over to drop off and pick up passengers. Theoretically you'd be able to grab a car as soon as you got to the station, if things were well organized that is, and it would then move back onto the main tracks and accelerate until it was trailing the next train down the line. (Or any other cars that were already trailing it of course.) Assuming it was successful enough you could then start eliminating trains over time until it was just the cars, which would let you speed things up since you wouldn't ever have to slow down or stop except at your destination. Obviously running them on tracks at first would make the programming a lot simpler and it would be a good way to get people used to them before they were more widely introduced.
Anyways, enough about that, i should go read up some more on the Propositions for tomorrow =P