I too use the Trip B to always track the Bat v Eng milage.
Unfortunately, the Pacifica resets after every 10,000 miles.
So, I record the values just before it hits 10K, then 20K, then 30K, and put them in a quick spreadsheet and calculate the totals, %Bat v %Eng, and total and monthly savings of the PacHy versus the previous Town & Country. (~$75/month savings for the same miles driven, btw).
It sure would've be an easy line of software to add to track the total lifetime Bat v Eng. Alas.