Poor gas mileage

[Stephen Tricamo]

My 2015 Lexus RX350 gets very poor mileage that changes with air temperature.  The lower the temperature, the worse the mileage.  The range goes from about 10 mpg  to 16 mpg.

I bought the pre-owned car in 2018 with 32000 miles on the odometer.  The gas mileage initially ranged from 18 to 21 mpg.  The gas mileage began to deteriorate about 1 year ago.

The engine light is not on. 

Any ideas about what the problem may be?

[Lexigrl]

Maybe this will help

https://youtu.be/_8KvLHrBkf0