Question About Fuel Milage Display And Range

[Pukka]

Hi I own a 02 ES300 and my range never went above 300 miles. For about 6~8 months, the range was like 230~260 but somehow it changed. and also when I actually drive the car measuring how much miles I run, I usually get around 340~360 miles per tank. It seems quite low especially during those 6~8 months when the engine even seemed retarded when the dealer couldn't find any problems. Is there any explanation to this?

Also, the average mpg usually says about 20.2~22.6 mpg even though I drive similar route, similar style most of the times. what do most other ES300s get? oh yeah it once hit low as 16 mpg when I was driving just normal...