1. The cost
2. Environmental impact.
It was kind of maddening to listen to, since yes the environment is important, but I'm not going to go bankrupt trying to save it. I don't have the luxury of the NPR host to pick and overpriced hybrid car. The complete obliviousness is staggering.
Here is Simon's money quote:
If you do the math, our hybrid purchases still seem to be driven by that aforementioned “self-satisfaction” rather than by true energy savings. But that math is precariously close to the tipping point, especially if you keep your car for a period of time.