There's a detailed explanation in this Forum itself. There were several additional features for Austin builds which now Fremont is serving up as well (starting Jan this year) - namely magnetic console, cargo cover etc. Austin build and paint quality and a single-cast framework did standout before Fremont iteratively improved their production lines in Feb and Mar (someone here posted an article on that). That said, I think at this point in time, they are more or less similar. Advantages that Austin had as a new and improved upon assembly line from Fremont has now gone. It's perhaps Fremont scoring one with the Matrix headlights. I'm sure, down the line Austin will catch up to that, and eventually both plants would mete out twins.