Yeah, the weight thing in some ways doesn't make a lot of sense, but in other ways it does make sense, so until manufactureres start adding bricks of lead to bump them into another category I wouldn't worry about it too much. The limit on the number of cars that qualify was intended to boost sales of domestic hybrids, so it kind of sucks for most people who want a reasonable car like the Prius since the domestics aren't offering cars yet...
Here's some estimates:
