33-14 MPG? What's Wrong?
 

When I drive my car carefully--doing some engine off coasting, keeping it under 55--shifting into neutral with engine on at short stops, etc. (1999 Toyota Avalon V6 Automatic)

Anyway, when I drive my car carefully I get upwards of 33 mpg.

When someone drives my car more normally, notably 65 mph or so, brisk acceleration maybe? It got 14 mpg. :facepalm:

The car has 200,000 miles on it. Photos of the engine etc. can be here seen on my website (Stock Avalon - HyperMPG.net)

A friend who knows about cars (worked on them for years) was very surprised that this care was in such good condition. He pointed to the transmission which had no signs of fluid leaks at all...perfectly clean. I mean the care does look good (except the oil addition area :) ) and seems to run well. It engine off coasts without complaint, etc.

My first guess would be that I need two new oxygen sensors. I have heard that they wear out and I do not know if/when they were changed. They looked really good from the outside when I got the car but...?

Car has new synthetic oil, clean fluids. K&N air filter (mostly because it is cleanable but a friend got it for me)

Thanks for any help!