Toyota Sienna AWD

Least efficient minivan
EPA City/Highway: 16/21

What, you ask in disbelief, is a Toyota doing on this list? Toyota, the green god who has bestowed upon mankind the benevolent Prius, has (drum roll) the most gas-guzzling minivan in the United States.

It's barely worse than the Dodge Caravan or Honda Odyssey, but it's a notable fact to poke fun at. Perhaps an environmental group will start burning Siennas to their deserved hell. Clearly, that's what this beast deserves.

(Thanks to Larry Ryan for pointing out that this EPA number is for the all-wheel drive model. Front-drive models get slightly better mileage at 17/23).