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Terrible MPG LS 500: 15MPG???

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Old 09-15-18, 10:13 PM
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seanspeng
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Angry Terrible MPG LS 500: 15MPG???

I bought this used at 2500 miles. When I got it, it showed 14.7 mpg, I thought that was something unusual. I drove 500 miles from San Diego to San Francisco and got 27 mpg average 78mph.

Now back to home, we drive a mixed city and highway, for this new tank (chevron) about 50/50 City/highway, I watched the mpg kept dropping, all the way to now 15.3 mpg. This is beyond miserable. I would expect it to be around 22-23.

Anyone else experienced such a terrible mpg? Could something be terribly wrong and caused it? What should I check?

Thank you in advance for sharing your information.
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Old 09-15-18, 11:10 PM
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Originally Posted by seanspeng View Post
I bought this used at 2500 miles. When I got it, it showed 14.7 mpg, I thought that was something unusual. I drove 500 miles from San Diego to San Francisco and got 27 mpg average 78mph.

Now back to home, we drive a mixed city and highway, for this new tank (chevron) about 50/50 City/highway, I watched the mpg kept dropping, all the way to now 15.3 mpg. This is beyond miserable. I would expect it to be around 22-23.

Anyone else experienced such a terrible mpg? Could something be terribly wrong and caused it? What should I check?

Thank you in advance for sharing your information.
It certainly sounds like something is wrong. After 12,000 miles, I'm averaging 25.6 mpg. That's about 80/20 hwy/city. I do 140 miles round trip to a client, all but 8 of those being highway miles, and when I fill up at the start, I average about 32.5 mpg @ 75-80 mph. When I fill up and drive 100% city, I get about what you're getting - 15 mpg give or take.

That's on a standard RWD LS (non-F-sport).
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Old 09-16-18, 03:22 AM
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nothing wrong, if the seller used the car for 2500 miles or it was a demo car at a dealer for that mpg is normal for the car.

instead of worrying, enjoy the car, reset the main mpg odometer back to 0 .. drive the car for couple months and you will be fine.

if your doing mostly city driving these cars will get 15-16 mpg.
that was why on my initial write up of the car i had an issue the lexus did a great job but with all the manufacturers getting on board with mid 20's combined or higher after 10 years of development a huge issue is at hand.

if you do low amount of miles annually it won't matter much just enjoy the car and your lucky to own such a beautiful car,

if you don't mind sharing what you paid for a used ls500 it would be great to see vs buying new

happy driving and congrats on owning one of the best cars ever made
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Old 09-16-18, 03:45 AM
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hi around the 22 1/2 minute mark in video he discuses 17mpg for his week of driving primarily highway
hope this helps
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Old 09-16-18, 07:46 AM
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@dsc07
Your MPG mixed sounds encouraging. What mode did you drive in? I mostly drive in normal, comfort and eco. You must have very gentle feet Do you use cruise control a lot? Mine is RWD Non Sports too.

I bought this at $91k out of door from a luxury car dealer. The MSRP is about $105K.

Will the MPG ever improve? Did the previous owner do a terrible job of break in?

In the video, he is getting 17mpg primarily highway, it almost sounds it's unlawful for Lexus to claim the 19-29mpg on the sticker.
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Old 09-16-18, 11:22 AM
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I have a RWD F-Sport LS 500 and I average at about +/- 20 mpg driving mostly on Normal mode. If I use Sport+ mode very often this drops to around 17 mpg or slightly less. Fuel wise, all these numbers are while using Shell 95 octane V-power mostly. I mostly drive in city (+/- 80%) with some highway drive.

The best ever consumption I manged to achive was +/- 35 mpg while driving at 84 mph (cruise control) for 3 hours in a long straight empty 4 lane road, so literally I didn't accelerate or decelerate even once at this strech of road. I was using 98 octane fuel in this particular event.
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Old 09-16-18, 12:31 PM
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Thanks for sharing. Maybe the fuel type is a big factor. I will try Shell next time.
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Old 09-16-18, 12:51 PM
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Originally Posted by seanspeng View Post
@dsc07
Your MPG mixed sounds encouraging. What mode did you drive in? I mostly drive in normal, comfort and eco. You must have very gentle feet Do you use cruise control a lot? Mine is RWD Non Sports too.

I bought this at $91k out of door from a luxury car dealer. The MSRP is about $105K.

Will the MPG ever improve? Did the previous owner do a terrible job of break in?

In the video, he is getting 17mpg primarily highway, it almost sounds it's unlawful for Lexus to claim the 19-29mpg on the sticker.
FIrst, you are correct, I do NOT have a lead foot, and as most of my driving is highway, I use cruise control most of the time. Not the dynamic radar cruise, I prefer the standard.

To your second question, I have a custom drive mode set with comfort chassis, power powertrain and normal climate. One big beef I have with the car is that you can't set the custom drive mode as the default. I mean really, if it's important enough for you to include a custom drive mode feature, why do you force people to select it manually every time they start the car?? On top of that, you have to wait 10 seconds or so for the system to boot up before you can switch to it. A terrible design decision, if you ask me.
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Old 09-16-18, 12:56 PM
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Originally Posted by dsc07 View Post
FIrst, you are correct, I do NOT have a lead foot, and as most of my driving is highway, I use cruise control most of the time. Not the dynamic radar cruise, I prefer the standard.

To your second question, I have a custom drive mode set with comfort chassis, power powertrain and normal climate. One big beef I have with the car is that you can't set the custom drive mode as the default. I mean really, if it's important enough for you to include a custom drive mode feature, why do you force people to select it manually every time they start the car?? On top of that, you have to wait 10 seconds or so for the system to boot up before you can switch to it. A terrible design decision, if you ask me.

CAFE and EPA regulations. Cars have to start in normal or eco mode, sport and custom modes have to be manually selected. Horrible Federal reguations not horrible design.
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Old 09-16-18, 09:57 PM
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Originally Posted by mjeds View Post



CAFE and EPA regulations. Cars have to start in normal or eco mode, sport and custom modes have to be manually selected. Horrible Federal reguations not horrible design.
Do you have a link for that? I find it hard to believe that there's an EPA regulation for something that 90% of most cars don't even have. Then again, we are talking about the US Government...
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Old 09-16-18, 11:29 PM
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LS 500 owners please share your experience with different brands of gas and their average MPG. I thought Chevron is good, but not as expected.
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Old Yesterday, 08:26 AM
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Originally Posted by mjeds View Post



CAFE and EPA regulations. Cars have to start in normal or eco mode, sport and custom modes have to be manually selected. Horrible Federal reguations not horrible design.
Sounds like that is not the case. This was taken from an article in Drivers.com, and the 3rd bullet point would indicate that there is no EPA regulation around drive modes not defaulting:

The EPA sent us a statement along with a 2009 policy document that said it would handle such driver-selectable systems "on a case-by-case basis." Here's how it shakes out:
  • If a vehicle has various drive modes but defaults back to Normal whenever you turn the engine back on, the EPA draws its fuel-economy ratings from the Normal mode.
  • But vehicles that default to a fuel-saving mode at start-up like the 2014 Jeep Grand Cherokee set economy as the "predominant" drive mode from which the EPA bases its MPG ratings, the agency told us.
  • If a vehicle has drive-mode system that stays in whatever you last drove, the EPA may not be able to establish a "predominant" mode. In such cases, "the vehicle is tested in the various modes and the fuel economy results from the best and worst modes are harmonically averaged," EPA officials wrote. "For example, if a vehicle has a sport mode, normal mode, and economy mode, the fuel economy results of the sport and economy modes would be averaged."
  • Automakers can (and often do) submit customer surveys or technical data that show that customers use one particular mode in their vehicles most of the time so if Honda determined that 80 percent of Civic owners drove everywhere in Econ mode, then it could request that the EPA rerate the Civic using economy-mode driving. If it's too early to assess the mode that drivers use most often say, with a fresh redesign or introduction then automakers can exercise "good engineering judgment" to determine what's predominant, the EPA said.
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Old Yesterday, 08:29 AM
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Originally Posted by dsc07 View Post
Do you have a link for that? I find it hard to believe that there's an EPA regulation for something that 90% of most cars don't even have. Then again, we are talking about the US Government...
as I understand from multiple articles I have read on the matter, the EPA regulations require them to test and post the results in the default drive mode of the vehicle. so if a Lexus defaults to normal, which is a balance of power and economy, then the EPA numbers on the Sticker are based off testing in normal mode because that is the default, If the manufacturer can prove that more than 50% of owners drive in Eco mode, then Eco mode can be used for the testing and those numbers can be the published numbers for the vehicle (i.e. Prius and Civic Hybrids).

if Sport was to be the default setting then the tested and published numbers have to be based off Sport mode, which on most vehicles sees an average drop of 11% in economy, some as high as 25%. This drop would then affect the Corporate MPG average that car manufacturers are required to maintain. So because of testing regulations, and in order to have the highest possible ratings, car manufacturers default to Normal or Eco mode.

https://www.cars.com/articles/do-all...1420663064071/
http://www.whyhighend.com/driving-modes.html
https://www.epa.gov/recalls/fuel-economy-label-updates

Last edited by mjeds; Yesterday at 08:36 AM.
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Old Yesterday, 09:46 PM
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Originally Posted by mjeds View Post
as I understand from multiple articles I have read on the matter, the EPA regulations require them to test and post the results in the default drive mode of the vehicle. so if a Lexus defaults to normal, which is a balance of power and economy, then the EPA numbers on the Sticker are based off testing in normal mode because that is the default, If the manufacturer can prove that more than 50% of owners drive in Eco mode, then Eco mode can be used for the testing and those numbers can be the published numbers for the vehicle (i.e. Prius and Civic Hybrids).

if Sport was to be the default setting then the tested and published numbers have to be based off Sport mode, which on most vehicles sees an average drop of 11% in economy, some as high as 25%. This drop would then affect the Corporate MPG average that car manufacturers are required to maintain. So because of testing regulations, and in order to have the highest possible ratings, car manufacturers default to Normal or Eco mode.

https://www.cars.com/articles/do-all...1420663064071/
http://www.whyhighend.com/driving-modes.html
https://www.epa.gov/recalls/fuel-economy-label-updates
Ok, that's just a methodology used by the EPA for measuring MGP, which is quite different from a regulation. Lexus is free to default the drive mode to the last mode used, like they did on the 460. But thanks for the links.
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