I am new to this forum. I recently bought a certified 2015 LS AWD with 30,000 miles on it. I have driven it almost 3,000 miles mostly around town. I get an astonishing 11mpg driving pretty conservatively. When I include some highway driving it jumps all the way up to 14. The only road trip I have taken was to Vermont from CT (500 miles round trip) where it got 24+. I have tried all three modes (eco, reg, sport) but nothing really changes. I took the car to Lexus for them to check out, and they said nothing is wrong. How can this be?

 

You should calculate your own MPG and not use the MPG readout on the instrument cluster. Also try resetting that readout.

 

There may be some insight for some of you here: https://www.clublexus.com/forums/ls-...is-so-off.html

 

Never trust a trip computers mileage. Run the figures by hand and reset the trip odometer between fill ups. Download the Fuelly app and log it ALL. I've religiously tracked the last 5K of my 2010 and have avg'd 21.2mpg with a best of 23.1. The first half was Eco Mode the 2nd in Pwr mode with winter fuel and 87 Octane. Doesn't make even the least bit of difference. In another couple tanks I'll try 4 or 5 tanks (about 2K miles) of 93 octane but I highly doubt it will matter.

The highway driving I do is messy. VERY messy. 70 miles each way, but broken up crossing a major city on 183 which is under heavy construction for over 15 miles and going through 2 other towns with traffic lights. The car never gets to run for more than 15 mins without hitting a stop light. I cross Austin, lights every mile or 2, then hit several in Lockhart, then several more and train tracks in Luling and on south. Always seem to catch the 2 or 3 just getting though the intersection at I-10 and 183 as well. Irritating is a understatement.



My old '08 LS 460:

 

I've experimented with different fuel grades and I have definitely seen a difference between 87 octane and 93 Roughly 3mpg difference. With 89 I split the difference. Now that we're on winter gas I'll see if my results are the same

 

Yes, I think it is. But that is an OEM bulb. I was hoping to get something a little whiter on the aftermarket.

Thanks!

 

Thanks for the info. I used my calculator to crunch those numbers, but I was also using the numbers from the trip odometer, which if the system was not calibrated correctly would also skew the results. I find it odd because it seems like I visit the gas station more frequently with this new car.

 

I'm glad I'm not the only one here who feels this way about the difference in my '07 and my '16.

 

It's the top picture, so they're HID's. Weird TRS doesn't list them for that year.

As for the MPG, it seems others here have gotten similar results with their '07 that I was getting. The tires were the original OEM size with no customizations to the car. I bought it as a CPO in 2010 and only Lexus had ever worked on the car. Same with the '16 and it has the original OEM wheels and tires size on it.

I'm thinking there is something else going on with the newer engine. Possibly smog settings or something. I will need to hook it up and compare some numbers between the '07 and '16.

Thanks!

 

Are you using Premium unleaded fuel? I know when I was trying to run mid-grade fuel my mileage plummeted.

 

I averaged 20mpg with mix city/highway driving on a 2010 LS460 with Premium Gas, I did get 30mpg in flat Texas roads to Oklahoma on a road trip but unsustainably high of course. You should check out the real world MPG of the LS500.

 

I have tried all three grades of gas. Doesn't seem to matter much. I am in Savannah area for the winter where it is far more level than in Southwest Connecticut. The average mileage has gone up to 19mpg with some highway, but mostly local streets. I have an AWD car. I think it may be idling to high, so I am going to give the local Lexus dealer a shot at that.

 

Grade of gas is a regional/geographical thing. Other countries have much poorer grade, their High Octane may only be the equivalent of our mid or low grade, thus Lexus just slapping a Premium Fuel required sticker on there. All the manufacturers do it.

As for the AWD LS's they are heavier, have more parasitic driveline losses, so naturally one would expect their mileage to be worse than a RWD only one. As to the idle, its got a tach what is it idling at? I'm thinking the idle rpm itself is controlled from the ECM.

 

It's lower than the LS460L. I am consistently getting lower mileage on my 2018 LS500 when compared to a 2017 LS460L and a few other MY LS460Ls.

 

tire condition /tire pressure is another factor impacting the MPG.