[modeless]

Starting and stopping does cost energy, but regen is pretty efficient and the lesser wind resistance of slow speeds mostly makes up for it. No, davidwhodge is right, the problem with short trips has to do with the fixed costs of "warming up" the car. Just looking at the energy graph in the car while driving it's easy to see that it's much more efficient after the car has warmed up.

[kube-system]

Yes, but electric motor regen usually does not work all the way down to zero mph. Usually it stops somewhere around 5-10mph, and the friction brakes take over. Slow rolling traffic that fluctuates between something like 10-30mph is very efficient, but stop and go traffic fluctuating between 0-20mph is pretty inefficient.