Cash for clunker

So what is really going on about this new bill being passed by the House? Here is the skinny. If you trade in your gas gussler "car" that gets 18 MPG for a new one that gets at least 22 MPG you will qualify for a $3500 voucher. The voucher can grow to $4500 if you get a new vehicle that gets at least 10 MPG better.