We have two 2007 RX400h's in our family and both are getting around 23-24 mpg in a combination of short-trip and local freeway travel. Perhaps not up to EPA numbers but neither of our vehicles have had their first oil change yet. If the break-in theory is true, our mileages may increase slightly. And, we both enjoy the performance of our cars and do not intend to "baby" them to try and achieve EPA mileage estimates. We find them to be fun, luxurious cars with a decent amount of performance thrown in. Also the technology is just really cool.
FYI, there have been many posts about Lexus's claimed mileage numbers. Neither Lexus nor any other manufacturer "creates" these numbers. They come from very specific testing based on a cycle dictated by the EPA. Blame the government's failure to simulate real-world conditions, or your specific driving conditions, not the manufacturers.
Tom