Hi all,

I am the proud and only owner of this 2017 Lexus ES300H. I purchased the vehicle with less than 1 mile on the odometer. Here's a quick summary:

MAINTENANCE:

• 193,000 miles (livery purposes)
• Transmission fluid replaced (not flushed) every 40k miles
• Oil changes around 10k or less
• New tires and alignment as needed
• New air filter at 190,000 (e very 30k)
• Suspension is not causing issues. Its holding up pretty well as I do mostly highway driving.
• Spark plugs were recently replaced at 190,000 miles and they looked like they could have gone at least 50,000 more miles.
• Fuel system was cleaned when the new spark plugs were installed.
• I installed Torque Pro with the bluetooth adapter and confirmed all field cells in battery are hovering around 16.1. - 16.3
  
• There are no check engine lights whatsoever
• This car drives and feels like the 1st day I purchased it!
• The transmission is buttery smooth and it accelerates fabulously.
• When I took the vehicle line to the dealer for the transmission service at 190,000 they did a full inspection and there was nothing wrong with the vehicle.

ISSUE:

• My fuel economy has been fairly consistent between Spring and Fall seasons, 33-36 MPG.
• At approximately 170,000 miles (June 2019 or so), my fuel economy began to decline.
• I'm averaging 29 right now! Including when driving on city roads.
• My driving habits have not changed. The above fuel economy that I typically average includes me driving aggressively, I won't list my maximum speed on the highway but trust me it's fairly aggressive.
• So in closing, there appears to be absolutely nothing wrong with the vehicle and there are no check engine lights or any type of errors being reported and the hybrid system appears to be healthy on the surface. Any thoughts on what to do? Thank you!

 

Did you go 190K miles on the original spark plugs?

 

Yes. After they removed the spark plugs they showed them to me and they told me I could have kept riding on these for at least 50000 more miles. They didn't look that much more different than the new set to be honest. But I'm not an expert at these things.

 

You may want to stop in at your local auto parts store and ask them to do a free load test on your 12v battery. I know it's not that old but you have a significant amount of miles on your car.

 

Thanks for the recommendation.

 

NAPA Auto Parts ran a test of the 12v battery with the vehicle powered off, and the results were it's performing above the actual specs on the battery itself. The associate said it is in outstanding condition.

 

What drive mode do you normally use? I didn't think my driving style was aggressive but I keep it on Eco mode now and my MPG went from 35 to 38 (A lot of stop and go traffic). I just changed my oil so that probably helped as well.

 

Hey Rogue! Well, I alternate between the three modes depending on my needs. I've maintained those habits since day one. So, that hasn't changed.Last week my average fuel economy was 30.5. This week or so it dropped to 29.5. Literally. There are no errors being reported in Torque Pro as well. All four new Tires were installed last week, tire pressure on all four tires peaks at 40 PSI in 70 degree climate on highway; alignment completed as well. No abnormal noises that would lead me to suspect bad wheel bearings or stuck brakes as well.

 

Is that mileage what the car reports? or what you actually measure with the odometer and fuel pump readings?

 

That's the reading from the odometer. Meaning that's the datof being displayed in the driver consul area.

29.5 After Refuel
29.6 After Reset

I reset the reading two days ago. I fill my fuel tank once a day. Average up to 350 miles a day.

 

I might get a 2nd opinion on your regular battery with that high number of miles. I read up on Camry hybrid forums because there are so few problems reported here with the es 300h and a few owners have been able to attribute sudden mpg losses to a declining battery or when they cheap out and buy the wrong battery.

Great to hear that everything else is holding up well!

 

Thank you for the feedback. I'll do that.

I think I may have found the culprit. Around the time I had a loss on mpg, my mechanic installed Primewell tires. To save money. I typically installed Bridgestone Ecopia Plus which have excellent fuel economy. I'm heading back tomorrow to install the Bridgestone tires. I'll report my findings over the next few days.

 

Not to tell you what to do but that sounds like throwing a lot of money at the problem. I’d do online research on the tire that you bought before shelling out all that cash.

 

I wondered about the tires when you described that you had installed them at about the same time as your mileage deteriorated. The low rolling resistance tires can certainly make a significant difference in fuel economy, but they aren't necessarily the quietest or best-handling tires. I wouldn't have expected more than 1 or 2 mpg difference though. Please do let us know if that resolves the mileage decrease!

 

Agreed..

a few MPGs but not what you are experiencing.. I'm hoping it's the 12v battery as it's an easy fix.
https://www.clublexus.com/forums/es-...l#post10488483
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