[EricDeb]

I will only support this when we are all required to use self-driven cars that can go twice the normal speed limit safely :)

[luser001]

Not going to happen imho: how will a self-driving car change the fact that stopping distance increases with speed?

Consideration for (unexpected) pedestrians (children etc) and cyclists seems to the primary motivation for low speed limits on residential side streets. I think that makes sense.

[mahyarm]

Better brakes. A porsche boxster will stop a lot sooner than your same weight honda civic.