2011 Lexus LS 460 - Mileage

Mileage is always 11>12 mpg. Is that normal for the model? About 80% of my driving is short distances, 20% at highway speeds (70mph).

Seems a little low. EPA rating for your vehicle and your driving style is about 16 MPG. So about 25% off. That rating is based on Premium fuel.

Thank you. (According to google and many YouTube posts, premium offers no mpg advantage over non-premium. Same for different octanes.)

I get about 15 mpg on my Honda Accord 4-cylinder on a cold day until it warms up. I commute on highways and end up with a full tank average of about 35 mpg. If you drive one way less than 5 miles consistently, I can see how your mileage could be significantly less than the EPA 16 mpg for city driving.

If you use regular gasoline, you might try a couple of tanks of premium to see if there is an improvement. I don’t know what sources you see online and on You Tube, but I’m always skeptical of those sources unless they can show real tests that verify their assertions.

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In my area owners are getting 17 to 18 MPG city driving. I used to work on some LS 460 limousines that were getting less than 10 MPG because of the amount of time idling with the A/C on so it depends on the use and trip length.

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You realize that per Toyota/Lexus your car requires 91 octane or better right? If you’re using regular then, the ECU is almost certainly pulling timing, which will reduce fuel economy.


I didn’t say I use regular, and I don’t.

I tried a month of Top Tier Premium, made no difference to mpg. How do you know the sources didn’t show real tests? Click and Clack, on the CarTalk site, quote a Petroleum Engineer study. In any event, I trust the sources.

Thanks for the info. My driving involves very little idling.

Click and Clack were talking about normal cars rated for regular gas. Some cars require or recommend premium. If they recommend it, you will get better power and likely better mileage by using premium. If they require it, you may cause engine damage by using regular.

shadowfax–No, they weren’t. All information from reliable sources is that octane and mpg are unrelated. I’m not interested in debating this, believe what you want to.

That really depends on the particular car. Fords with Ecoboost engines adjust their boost and timing based on gas grade, significant change in hp, and I bet some change in mpgs.

To say they are ‘unrelated’ is patently false. To say the relationship is not significant, not enough to justify the cost of premium, that’s probably true.


Most modern cars adjust for octanes. I stick by “unrelated,” any differences in mpg are so small as to be statistically irrelevant.

It’s not that your sources are wrong. It’s that you don’t understand what they’re saying.

Heres a good discussion:

Engines require a good deal more gasoline, as much as 2-3 times, when the coolant is below the designed operating temperature. . Next time you take a longer trip, do a proper mpg measurement: After the engine has warmed up, pull into the nearest gas station and fill the tank. Then drive to the destination, and fill the tank again. mpg = miles between the two gas stations/ number of gallons you purchased.

Whatever you say, shadowfax.

Every time I fill up, for the past 9 years, I divide the miles on the trip recorder by the amount of gasoline I purchased, and note the result, to two decimals. I then reset the trip recorder to zero and repeat. MPG has never been more than 12.3, the overall average is 11.4, over some 20,000 miles. That’s pretty close to the dash display for average mpg for the life of the car (I bought it used): 13.6.

Will using a higher octane fuel than required improve fuel economy or performance?

It depends. For most vehicles, higher octane fuel may improve performance and gas mileage and reduce carbon dioxide (CO2) emissions by a few percent during severe duty operation, such as towing a trailer or carrying heavy loads, especially in hot weather. However, under normal driving conditions, you may get little to no benefit.
From fueleconomy.gov

The operative words are: under normal driving conditions, you may get little to no benefit.**

You missed the important part for your car:

What if I use a lower octane fuel than required for my vehicle?

Using a lower octane fuel than required can cause the engine to run poorly and can damage the engine and emissions control system over time. It may also void your warranty. In older vehicles, the engine can make an audible “knocking” or “pinging” sound. Many newer vehicles can adjust the spark timing to reduce knock, but engine power and fuel economy will still suffer.