39mpg!! original battery can last 300k miles

https://www.clublexus.com/forums/hybrid-technology/785590-miles-on-your-rx400h-7.html 

39mpg!! As a bonus, the hybrid battery behavior improved. It now cycles between roughly 20% and 80% charge, only going into the green during long highway runs. Fuel economy has improved too: about 39 mpg on long trips and 35.7 mpg on shorter ~14-mile runs