Here’s a word problem for you green-minded types:

I live in Brooklin. I want to go to Kennebunk (actually Arundel, to Wildfire HPV, but I would use Kennebunk as my base since my partner is there for business) to test-drive recumbent trikes as a first step toward greening my transportation. I have a regular, non-hybrid car at my disposal. If I drive it will take me about 4 hours each way, and about 17 gallons of gas round trip.

I can catch a bus in Bangor, about an hour away in the wrong direction, but not in Ellsworth, which is more like 30 or 40 minutes away. I can also catch a bus in Belfast, an hour or more away in the right direction. Neither of these buses will stop in Kennebunk. They will only stop in Portland. Portland is 30 minutes from Kennebunk. My partner is in Kennebunk with a Prius. She can come get me and return with me to Kennbunk, adding one Prius-hour of driving to the total carbon footprint of this trip.

If I do this and take the bus, I can return with her to Brooklin in the Prius. However, we then must drive to Bangor to retrieve the other car, adding two Prius-hours of driving to the two regular hours of driving to the carbon footprint of the trip. Alternatively, if I take the bus from Belfast, the car pickup will be on the way home.

“Regular driving” is about 20 mi/gal and Prius driving is about 45 mi/gal.

What is the best way for me to get to Kennebunk?

Do I (a) Drive to Kennebunk (8 hours of driving for the round trip)
(b) Drive to Belfast and take the bus from there to Portland (3 hours of regular driving, plus on extra Prius-hour, plus the bus, which is $35 and 9 hours)
(c) Drive to Bangor and take the bus from there to Portland (2 hours of regular driving plus 3 Prius-hours, plus the bus, which is $25 and 2.5 hours)
(d) wait for her to get home with the Prius and then drive to Kennebunk as a separate trip (8 Prius-hours)

Bueller? Anyone?