Hi
Yesterday I drove for 2 1/2 hr from Stavanger Norway to Lindesnes this is "country road" up hill and down hill. Speed between 40-55 mph. On that distance I made 38.2 mpg (UK) or 31.8 mpg (US. To and from work at home, short distance I only make 28 mpg (UK)
Previously I hade a BMW X5 diesel and to and from work the consumption was more or less the same as the RX400h but long distance on Norwegian rollercoaster roads the RX400h is far better.