My 2013 when new would display ranges after fill-ups in the low 300 mile range. Over time the range after fill-ups kept getting lower and lower, and is now down to around 260 miles. To try to get better accuracy I have tried zeroing out every mileage function I can find, but still no luck.
Any suggestions?

Is there some hidden cumulative value that the vehicle uses? If so, maybe it's factoring all those trips in the past when I was towing a horse trailer. I use another truck for towing now, and would like to reset the Lexus so that the range starts out with a more realistic and current projection. My actual range is around 330 miles where and how I drive these days.

 

Don't know if there is a specific procedures to actually reset range (I could be wrong). If I understood this correctly, the range is calculated based on last speed and fuel consumption samples. If I would stop at pump right off the freeway travel, it would result a higher range vs. if I went through a lots of traffic stops before arrived pump. One thing that you might want to try is drive the car to near empty, clear out all the data such as average fuel consumption, average speed traveled, etc., drive the car as you normally do for a short distance, then stop the pump and fill it up. Maybe that will give you a more accurate estimate.