The first stop on our personal version of the Green Buildings Open House tour on Saturday was off the beaten path, if not the grid, to the several buildings of the Sirius Community in Shutesbury. Even before we arrived, the last dot of the Prius's gas gauge was blinking, with no gas stations in sight for several miles back.

"If your car used vegetable oil, we could help you," our tour guide said. She also told us about the community's root cellar, which was being put to good use again this fall, with perhaps a little more urgency this year because of concerns for the economy, but with the same practices the community has always strived for.

"That's part of trying to live efficiently," I observed, sagely but glibly, "you don't do it only when you have an extra good reason to."

I had never done much hypermiling, which has become a cultish pastime of some Prius owners, trying to extend the gas mileage of the car by relying as much as possible on battery power, a practice made easier by the power-use animation on the car's video screen. But especially after our GPS mistakenly led us around a long triangular loop back to where we started, we were highly motivated to try.

We were aided greatly by having a significant uphill lie, but even on the straightaways, we were able to keep our momentum without engaging the gas engine by feathering the accelerator. I was fairly impressed with my hyper-skills as I pulled into the gas station, at least until the conversation I'd had about the root cellar starting replaying in my head, especially my response.

We could be hypermiling every mile, instead of just when we have an extra good reason to.