"It's not likely that people are actually thinking about fuel economy that way, that they can splurge on a less fuel-efficient vehicle," said Archsmith. "It is probably operating through other attributes of the car that are associated with fuel economy. So I have a car that is small and fuel efficient, but it isn't as comfortable and can't fit the kids. Then, I tend to buy a bigger second car. It is more likely utility based in some way, but it is correlated with fuel economy nonetheless."