Was that for private vehicles that people bought themselves and paid for the fuel and electricity themselves? I remember a few years ago a study out of Europe of plugin hybrids that found the drivers didn’t plug them in. One the details came out we found that those were corporate vehicles assigned to them mainly for business use. They were reimbursed for gasoline purchases but were not reimbursed for electricity. The result was that they chose the option that results in less personal cost to them.

I find it hard to believe that people will elect to spend more money on a plugin hybrid and then not bother plugging it in as long as they have an easy access to a power outlet. Just the extra cost of gasoline in that scenario should overcome the minor effort of developing a habit of plugging in when you get home.