Hey there Bwilson. I'm not really 100% up on everything, but from what I know on CleanMPG is that there are 3 batches of "Prius III" HSI controllers.
The first batch was 5~6% high, across the board.
Batch 2 was ~3%
Now, they are within 1%.
2010 Prius – 6 mpg FCD vs. actual FE over report… - CleanMPG Forums