1.6 gallon toilet
I think the year Congress mandated 1.6 gpp was 1995.
I recently renovated one of my bathrooms and didn't really want to give up the more powerful 1940's toilet for the newer low flow types. All the ones I've used in other houses just didn't work right(had to be flushed multiple times anyway and used even more water).
Anyway, I talked to a contractor friend and he recently installed some fancy $400 one piece toilet that was supposed to work well. I think it was one of those pressure charging types. Well, in less than a month he ripped it out and smashed it with sledgehammer(I wish I was there to see that), he hated it so much. He then installed a Kohler Wellworth model and said he was pretty happy with it.
I decided to get one too, and it is working pretty good so far, and my opinion has been reversed on the possibility of getting a decent toilet with these low flow rules.
A White one will cost $99 at the home depot.
Other colors are about $130.