rcy

Are you talking about the instant display or the average display? If it only had 18 miles on it, and you're talking about the average display, it's bound to get better as mileage is put on the vehicle.

kiwi

i have noticed the exact opposite, i have a 2004, and no matter what fuel i put in i get the same milage, the only difference found is a noticeable power difference (passing on the highway for example)

daryll40

The sample that the original poster gave is way to small to determine anything.

jfelbab

I have several years of data on my 2004 RX330 to support the claim of Lexus114, that premium gives me 1.5 to 2 MPG higher mileage (measured, not the display). This is noticeable on the freeway and at steady (cruise controlled) speeds in the 70-80 MPH range. I've made many cross country trips, using the same routes and have concluded for me and my RX330, premium is less expensive per mile than regular.

That said, I see no difference in MPG in the city using premium or regular. I can feel the difference in power but not measure the difference in MPG in city driving. It is only when I get on the freeway and drive cross country that I can actually see and accurately measure the difference.

I can also smell the difference in my RX. When I burn regular and I'm a bit heavy on the gas I smell that rotten egg smell. I don't get this when burning premium. This vehicle has been checked by Lexus on several occasions to determine proper tuning. It has also had a TSIB applied affecting this sulphur odor which helped but didn't eliminate it. That smell is from poor combustion artifacts. With premium there is no odor which implies more complete combustion.

This may not be the same for everyone but I'm convinced, premium in my RX330 is cheaper per mile than regular gas.

I should also add the premium costs me 20¢ per gallon over regular gas. If this delta is different where you live premium might not be more economical.

RX330inFL

Please keep in mind that we are talking about a 3rd Generation RX here. Am guessing a 2012, though lexus114 did not indicate such. He just stated that it was new. With the new 3G 3.5L V6 Toyota/Lexus made changes where premium fuel was no longer required as it was for the 2G RX 3.5L V6. This engine is different, at least in engine mapping of the computer(s), from those in any of the 2nd Generation RX350 vehicles. It also has a 6-speed transmission compared to our 5-speed. A bit of a stretch to make any statements regarding the 2nd Generation based on this new model. Premium fuel may be more beneficial in that model. Perhaps a question for that forum.

I never trust the computer readouts. They are far from accurate, IMHO, and there is little information which discusses what goes into the calculations displayed for MPG on that display for either value. You can only make such a determination with a large statistical sample over time and using the miles traveled over fuel used formula. Even that can have a large margin of error.

I am with the group stating they do not see a major benefit in their RX330 using premium fuel. Yes, better performance, slightly better MPG in some instances. Still, for day-to-day driving on the back roads here I see no real difference just puttering around. No problems with any sulfur smells over the years.

Here in my area of FL it is usually 25-30+ cents more for premium. If I stray out of my area there is a BP where premium is only about 13-15 cents more than regular. In those cases I will treat my RX to premium as I will be out on the highway for long stretches where the difference will be noticed.

daryll40

This seems to reinforce my thinking to use "middle of the range" 89 octane for our mostly city driving 2006 Second Generation RX330.

RX330inFL

That may be true for the mountains there in Pittsburgh and PA. Just going to the store you are going up and down hills. I live in flatland here in FL. Biggest hill I come across most days is the driveway leading to my house.

daryll40

That's sort of why I buy 89 octane. It's 10 cents/gal more here whereas 93 octane is 30 cents more. Yes, the hills of Pittsburgh are taxing on a car. So I think 89 is the sweet spot in terms of both cost and octane.

Benzat17

i always thought higher octane means burn faster ( coz its cleaner ) which means less mileage ?

rcy

Google my friend, Google.

350250

i live in toronto and i put +94 octane in my 08 is250 and the wife runs the same in he 08 rx350 always used +94 in my cars notice the difference runs amazing better engines response better performance but im sure in the u.s you guys dont get +94 gas used alot in canada for racing and dyno pretty much better perfornance

RX330inFL

Best we can do here in FL at the normal pumps is 93 octane. However, there is a shop I use that has available 100 octane as well as ethanol free fuels which I need for my older vehicles and my tractor.

Still, for day-to-day driving on the roads here in my area 87 octane does well.

rcy

Here in Canada, the high octane fuels (91and higher) have no ethanol (at least with Shell, Petro Canada and Esso, all of which I've emailed about the use of ethanol). That alone should mean higher mileage with the higher octane as gas/ethanol gives less mpg than gas without ethanol.

RX330inFL

We are subsidizing corn production here in the states. Only thing it did was raise the price of fuel and food.

Emilaman

Yes, and it is tested by me, there is enough difference in performance between 87 and 91 to pay 20 cent more per gallon. And there is also huge difference in gasoline brand, on Chevron premium gas im driving twice more than on BP (ARCO) premium gas