Not a materials improvement, but an improvement in the shape of the bowl, so mostly a direct result of better hydrodynamic and CAD modeling.
Not only do they use less water, but they /smell better/ -- most of the "smell of urine" results from the pee being added to, and reacting with, water, so no water, no noticeable odour.
Not only do they use less water, but they /smell better/ -- most of the "smell of urine" results from the pee being added to, and reacting with, water, so no water, no noticeable odour.