Surprisingly lower mileage than claimed.

 "Tests of Priuses fitted with $10,000 lithium-ion packs from battery maker
A123 Systems Inc. found fuel economy rose only to mid-to-low 50 miles per
gallon from the standard Prius's 46 mpg rating, Toyota said. The results of
the tests by Google Inc.'s Google.Org, Consumer Reports and Portland General
Electric include energy used to recharge the extra batteries."

http://www.bloomberg.com/apps/news?pid  601101&sid=arvp1GgT74o8&refer=japan

Seems to me a lot of Prius drivers do this well without the upgrade.

 

Was Istoben wrote:

Full cycle cost is wholly dependent on plug-in recharging cost per kwH
compared with pump fuel, with locally high electricity costs effectively
redlining sales of PHEVs.

 

Right.   The cost equivalence would be sixty cents a gallon where I live.
After reading the article I felt the Volt's advantage would be it's ability
to achieve highway speeds during all-electric operation.  With either, a 30
mile daily round trip commute at speeds below 40 mph (nightly charge) should
yield an exceptional mpg equivalence.  That advantage will likely be lost in
short order considering 90% of my electricity comes from coal.