It sounds like the beginning of a bar room joke.
Two self-driving cars are headed down the highway when the lead car decides to speed up to avoid being rear-ended by the second. That car, in turn, slows down to avoid hitting the first. Then a third car suddenly comes between the two, prompting the slower car to change lanes to avoid and accident.
The problem: There are cars in the lanes on either side of it.
What’s an autonomous car to do? The answer is no joke. 
 By Lucas Mearian for Computerworld