I found a new source for scientific reliability data, and it tells a much different story, than consumer union (CU) and JP Power
Consumer Reports and JD power data are based on peoples opinions and memory.
I've owned a Toyota Prius and can state that it was the not terribly reliable, in spite of CUs stellar rating.
So far my FiST has been perfect, but I only have 4000 miles on it.
An auto warranty company out of England publishes reliability data based on their experience paying for repairs.
It seems to me that this data would be more scientific, because human judgment and emotions don't get in the way.
The Fiesta is rated with a score of 24, which is good. the Focus is 56 still good (both cars are rated very bad by CU)
This is comparable to the Toyota Prius and Corolla, rated at 36, 52 (both cars are rated very good by CU)
And example of a very bad car is a A BMW 3 series with a rating of 205, very bad.
http://www.reliabilityindex.com/