If you surfed through Yahoo!'s home page this morning, you may have noticed the good news for Toyota Prius-driving men everywhere. A study by General Motors announced that 88 percent of women polled said they'd rather talk to a guy who drives a new fuel-efficient vehicle than a gas-guzzling sports car. But hold on a second before you run out and buy a hybrid, because that number could be suspect. Self-reported survey data is known for being notoriously problematic; people want be liked, even by strangers they'll never meet again, so they're more likely to say what they think will impress the questioner. Green may be in style, but what the GM study may really being showing, unfortunately for heterosexual male tree-huggers, is not that women everywhere want to talk to, date, or marry environmentally responsible men. Rather, it could be that they know they're supposed to want that. This gap between idealized behavior and reality brings to mind the Bradley Effect, which analysts use to explain why black politicians often perform slightly worse in elections than they did in pre-polling. Voters might say over the phone that they support a black candidate in order to impress pollsters with their progressiveness, but in the privacy of the voting booth they are free to let racial biases loose. The Bradley Effect has received plenty of publicity during the 2008 Presidential campaign on the occasions in which Sen. Barack Obama's poll numbers and election tallies didn't jibe. No one, to our knowledge, has measured female behavior to find out whether women actually talk more to men with fuel-efficient cars. Thus, we can't tell for sure whether the GM study represents a version of the Bradley Effect based on eco-shame, or a real shift in social perception. But it seems unlikely that 9 out of 10 women now look at a bright red Ferrari and see carbon emissions where they once saw luxury, money, or power. So drive that compact car with pride, men of America. Just don't be surprised if your miles-per-gallon doesn't always work as a pick-up line.