dchar

There has been many publications stating that using higher octane than what is recommended to improve performance and efficiency is a myth, especially if you have a newer car. Just do a google search and you won't find an article anymore stating that you should only buy higher octanes to get the most out of your car.

The only time to use higher octane than recommended: "If your car does not ping on regular, then there is no reason to seek a higher-octane gasoline. The anti-knock level of the regular in this case is adequate for the engine. But as a car gets older, depending on how the car has been driven and cared for, it may need a higher-octane gasoline anytime between four and six years. That's because carbon deposits inside the cylinders raise the combustion ratio, which in turn raises the engine's octane rating. You may notice that your car operated fine on regular fuel when it was new, but pings on regular as it gets older. So, the higher-octane fuel is not something to pamper a new car with but rather help keep an older car running properly." Many articles even state that you don't even have to constantly use the higher octane in the older cars, just once in a while when you feel pings.

Sure you might have experienced "higher" mileage...but there are too many other variables to consider. Did you control for weather, traffic, traffic light coordination, etc.? I'm not sure if the ES300h requires premium, but if it doesn't...you're wasting your money (which doesn't bother me, but others should know to prevent this myth from perpetuating).

swfla

iTrader: (1)

I have a 2009 es 350. I get 25 mpg combined according to the display. I use 87 octane
(R+M/2). I recently put in a full tank of 93 octane and got the same mileage. I'm now calculating my mpg using the odometer and gallon reading from pump on my next fill
up. So, my results showed no change in mpg driving the same route I always use.

lesz

I agree 100%. Unless the compression ratio for the vehicle is well over 10:1, which is not the case for the ES, there should be no benefit at all in either performance or fuel economy to using premium fuel.

As you stated, there are lots of things that could have led to a change in mpg from one tank to the next, including driving conditions, temperature, driving habits, etc., and, even if there was some benefit to mpg from using premium fuel, you would not be seeing that benefit until many tankfuls of that premium fuel had been used.

My driving is done mainly on country roads. While it is not true "highway" driving, I don't have much stop-and-go driving. I've used 87 octane regular in the ES since it was purchased 2 years ago, and my actually calculated mpg over that time has been a little over 32 mpg. While I know that, if I were doing more stop-and-go driving, I would not be getting 32 mpg, I can't imagine that premium fuel would be allowing me to do any better.

Earlier versions of the ES with the same 3.5 liter engine said that premium fuel was recommended, but that 87 octane was satisfactory, but the reason for the premium fuel "recommendation" had nothing to do with performance or fuel economy. Instead, it was because the EPA regulations at that time allowed Toyota/Lexus to get a better emissions rating with that recommendation.

The manual for my GX has a similar statement saying that premium is recommended but that regular is okay. The compression ratio on that vehicle's V8 engine is 10:1. I've been using regular fuel in it since it was new in 2005, and I still consistently get fuel economy better than the EPA highway rating.

In most parts of the US, premium fuel is typically $.30-$.40 per gallon higher than regular fuel. That would mean that, even if premium did give you better mpg (which it doesn't), it would have to be at least 15% better to make it a financial winner, and that just isn't going to happen.

chromedome

How about luxury fuel?

Anyway, the OP is asking similar questions on the 3IS forum comparing the IS250 vs. IS350. If he/she is really concerned about fuel consumption, especially with lots of city and stop-go driving, I would recommend the hybrid ES. I'm getting 44 mpg on my current tank with mainly city driving.

It all depends on the OP's usual driving conditions and the annual mileage. Hybrids don't really pencil in if you don't do a lot of miles per year. You also have to put up with hybrid quirks like regen braking and the EV/ICE transitions, whereas the ES350 is a straightforward, quiet and powerful cruiser.

lexusplz

I'm also considering the IS 250 as my next car too. Coming from a Toyota corolla that I spent about $32 regular (87) weekly (~50miles round trip daily work), I just want to see how much more gas I would need to pay when I switch to a lexus, IS 250 or the ES 350. From what I've research, ES 350 uses regular gas (87) and IS 250 uses premium (91). On the other IS thread, people say they fill up at around $45-60 weekly. Here, I read people fill up about $50-60 weekly for ES 350 with about 20 miles left to spare. I know the mileage varies. The IS 250 have a 2.5L engine (premium 91) which fills up less than the ES 350 with a 3.5L engine (regular 87). It sounds like the IS 250 cost more to own. Also, I have to face the LA traffic everyday here.

dchar

If you're considering the IS250, then you'll probably get worse gas mileage due to the underpowered engine. You'll be stepping on the gas more to get going. With only 204 hp, 185 lb/ft torque, and 0-60 time of 7.7 secs in the IS, you'll be underwhelmed by the performance especially compared to the healthier 268 hp, 248 lb/ft torque and 0-60 time of 7.1 secs in the ES. You might think the ES350 weighs much more than the IS250 due to the extra space, but it's only 88 lbs heavier so the mass to move is about the same. Running cost will probably cost more in the IS250, especially if it requires premium. Lexus just needs to retire the 2.5L V6 and slot in the 2.0L turbo inline-4 (238 hp, 258 lb/ft torque). So if you're still considering the IS, definitely go for the IS350 but you'll be paying even more for gas.

Since you have to face LA traffic everyday, then the extra space and suspension compliance of the ES would be a great commuting car. The extra length of the car might be a little more difficult to park downtown, but just a small sacrifice for more comfort. Not sure how tall you are but I felt the IS was very cramped when I had it as a loaner. I'm 6' and my seating position causes rear passengers to have barely any legroom, and the wide center console cuts into front legroom too.