Bought a 2006 Lexus ES330 w.50,000m. Only getting 18mpg, city and 22 hwy using

Same car, same mileage. Bought some mass air flow sensor cleaner, installed K&N air filter, ran some redline FI cleaner, run 91 since the day I've bought it, and then reset the ECU by disconnecting battery. I'm up to about 20 around town and like 25 highway. That's up from about 14 and 20. I'm happy. Next is plugs and O2 sensors. Good luck with that. I'd love to know what else you've done or what else you will do to beef up fuel economy. Keep us posted!

No check engine light. 18 city/27 hwy is what 'Edmonds' review has listed. What's your average speed on highway driving? Faster , like consistently 75 or over will drop the mileage a little , but I don't think it should be as little as 22MPG. Maybe it would be worth having a shop (preferably one you are familiar with and trust), monitor it's fuel trim and see if it's running a little rich , but not enough to turn on the check engine light.

Why are you using high test?. Just use good quality regular like Shell or Chevron. 20 mpg more or less is what you get on these cars. Acceleration rate and speed Will effect mileage.