I bought the Rx450h after leasing the Rx400h, buying it off lease and giving it to our son. While the Rx400h was great, the Rx450h is a great improvement with even better mileage. The size is perfect - larger than the 400h but still small enough to be nimble in town and larger enough to feel roomy on the road. We get 28mpg+ (about 1mpg better than the Rx400h). I love the improved comfort, the ventilated/heated seats, the technology plug ins; did I say it was great throughout the last 3 snowstorms that hit Washington, DC? The technology and interior design are improvements over the the rx400h. I loved the RX400h I bought he RX450h when the 400h lease was over.
improved size, comfort, reliability, service (almost 24/7), technology
remove the "Locks" on the navigation and phone when in motion