Autos: Does the term "Fuel Efficent" have an actual number?

Is there a benchmark number for a car being “Fuel Efficient” over not being fuel efficient?

That is, can a car maker state that a car is fuel efficient, regardless of the number? If it can’t, what is that magic number?

I’m talking about cars made in the past 4 years.

I wouldn’t think you could have one figure. With my wife, a couple of dogs, stuff, and running 75-80, our Cavalier gets well into the 30’s, which I would call fuel efficient. Doesn’t match our daughter’s Civic Hybrid. Now sometimes we have made the same trips sharing our friends’ Suburban. I am not sure what sort of millage it gets, but far less than our Cavalier. Still, it is far more efficient for 6 people, dogs, and stuff than 3 Cavaliers would be.

I think efficiency needs to be as compared to other alternatives. My little pick up is less efficient than my Cavalier for hauling me and one dog around town. Now add a load of building supplies? I endure the poorer millage most of the time for the additional utility occasionally.

Before HD went out of business here, they had a nice big pickup you could rent for $20 for the first hour. A fuel efficient solution for those with infrequent needs for a truck.