According to CBS Chicago, two brothers from Du Page county, Illinois - Chris and Andrew Ewert - have modified a Prius to get 100 mpge (the "e" here being very undefined in the original source), simply by adding more batteries (battery type? also undefined) and a charger to the stock model. While techy details are not forthcoming about this particular PHEV conversion, at least one message comes through nicely: "My brother and I built this, and car companies should be able to do it, too," Chris said.
If you'd like to see some technical information on how a Prius conversion looks like, check out what Kim Adelman is doing.
[Source: CBS Chicago]