Dear Car Talk:

Do Prius owners really think they need to set the (slow) pace for everyone else?

Very often, at the head of a line of slow-moving vehicles is a Prius, or one will pull out in front of another car and slow down every car behind it.

Is it because the car cannot accelerate, or is it because the owners of that particular car feel the need to control others? -- Susan



I don't think it's either one, Susan.

We know a famous researcher named Dr. David Giovannoni. We call him Dr. Joe Baloney. He once explained to us that humans (and organizations) achieve what they measure.

So, for instance, if you want to lose weight, what would you do? Well, you might cut out sweets, drink water instead of soda and maybe start to exercise (Note: we're talking about you, not me).

Then you'd get on a scale. And if the number on the scale was lower than it was the week before, you'd keep doing those things, because you'd know they're working.

You achieve what you measure.

Now, who buys a Toyota Prius? Someone who wants to get better gas mileage than the rest of us mortals. And guess what a big screen on the dashboard of the Prius does? It measures mileage. Constantly. By watching the numbers change on that screen, Prius drivers learn very quickly that by accelerating very gently, they can coax their mileage up from 53.8 mpg to 54.1 mpg.

That makes them feel good. So they learn to feather that gas pedal and take 25 seconds to get from 0-60 while you're cursing at them through your windshield.

It's not that the Prius can't accelerate. It will accelerate like pretty much any other car if you put your foot down.

And it's not that they feel a need to be controlling. They're just pursuing their personal goal of maximizing their mileage -- because they care about it, and they're constantly measuring it.

Likewise, if you measured your blood pressure, Susan, you'd probably find that it goes up when you're stuck behind a Prius. If you took a few deep breaths and said to yourself, "How nice, there's a person who cares about the planet and is making the world a better place by wasting less fuel," you'd see your blood pressure go down.

Then you'd throw the blood pressure monitor out the window and pass the Prius with a few choice hand gestures.