The merger, announced today, between Zipcar and Flexcar (whose corporate identity is Mobility, Inc.) is a survival strategy in a business that pits our desire for a greener future against the hard reality of expensive assets and resource allocation.

I discovered Flexcar a few years ago, when a friend went to work at its Portland office. Soon I was trying the service as part of a "low car diet," giving up my car in order to walk, bike, bus, car share. I loved the idea but was struck with the high cost and relatively low efficiency of the service; in order for the service to pencil out (and pay for those many hours cars spent sitting in festively-marked parking spaces) the hourly rates for using a car were $8 to $9. When you consider a typical person's car usage -- get up in the morning, drive somewhere, leave car there for several hours, drive home, doing errands along the way -- you quickly realize it doesn't pencil out ($90-100 a day to use a car). However, if you're only using cars for very brief errands; picking up recycled lumber for your chicken coop, for instance; $20 a trip versus $300 or more each month to maintain a car, works out.

So it's economical for an individual who makes (say) a couple of monthly jaunts to an out-of-town picnic site or party each month, one errand around town in a week, and a weekend bed & breakfast getaway every year. It's sensible for corporations who would rather put the liability involved with company vehicles on another entity. But does it pencil out for the asset and liability holder: Flexcar and its chief competitor, Zipcar?