Incentives for hybrid vehicles ineffective?

Rebates wouldn't bring more into the Prius?

According to a new study, people that buy hybrid vehicles would buy them whether tax credits are available or not. Moreover, if hybrids were not available, these people would be buying other fuel efficient products. Therefore, according to an author of the study, those buying hybrids are having a negligible effect on the environment and fuel efficiency.

I say, poppycock.

Finish: Incentives for hybrid vehicles ineffective?