I now appears that perhaps NOSPINZONE is right. This latest tank of 87 octane got me 16.2 MPGs. Much closer to the 17.1 I was getting with 90 octane. I'll report in again next week after burning thru yet another $80 (or more!) tankful!

 

Odo miles Gal mpg
405 405 25.583 15.831
962 557 33.431 16.661
1229 267 16.113 16.570
1550 321 18.940 16.948
1766 216 13.028 16.580
2133 367 18.793 19.529
2371 238 13.223 17.999
2629 258 15.018 17.179
2893 264 16.334 16.163
3155 262 14.329 18.285
3497 342 15.394 22.216
3723 226 14.031 16.107
4133 410 17.488 23.445
4319 186 9.946 18.701
4539 220 13.239 16.618
4816 277 16.081 17.225
5239 423 18.379 23.015
5574 335 18.120 18.488
5720 146 10.350 14.106
6137 417 16.641 25.059
6401 264 15.103 17.480
6665 264 17.506 15.081
6986 321 16.357 19.625
7306 320 14.441 22.159
7658 352 18.960 18.565
8040 382 16.215 23.558
8318 278 14.225 19.543
8719 401 17.350 23.112
9016 297 15.945 18.627
9368 352 15.035 23.412
9691 323 16.723 19.315
9926 235 13.972 16.819
10284 358 16.750 21.373
10602 318 18.147 17.524
10960 358 15.684 22.826
11331 371 19.342 19.181
11627 296 16.483 17.958
11953 326 15.588 20.914
12291 338 15.279 22.122



643.566gal 19.10mpg average since new

This is every drop of gas put in my '07 LS460. The gas put into the tank by the dealer at predelivery service was regular--every tank I purchased was premium. I have made a 400 mile (roundtrip) highway trip each month, but the rest of the miles were around the Dallas-Ft Worth metroplex (a mix of freeways, tollways and city streets)
I also have a 07 RX350 which my wife drives--it is averaging 19.56mpg after 18,893 miles on Mid-range fuel. Almost all city driving.

 

Thanks for posting that. It is very interesting. Your 19.10 average DALLAS MPGs on premium compares to my 17.1 PITTSBURGH MPGs on premium. (Dallas is MUCH easier driving than Pittsburgh). It doesn't really address, however, the point of this tread which is to assess the value of buying the recommended premium gas versus the cheaper 87 octane.

Just as an aside, how do you know the car came from the dealer with 87 octane gas or is that just an assumption? And if you really know it, why wouldn't you go bust their tailpipes with Lexus for delivering the product with something lesser than recommended?

 

I was told by the dealership's gen mgr that they only have one grade of gas in their storage tank--Regular. And that is what they fill all cars with--loaners, demos, and new cars for delivery

 

I can't believe that any dealer would do that let alone admit it! And while I guess I would not want to be the customer that turns them into Lexus, I cannot imagine that Lexus corporate would permit that. All of that being said, I am sure that most dealers just buy the cheaper gas too (but keep quiet about it...most probably do not have their own gas and buy from the regular gas stations).

 

I've been siphoning 1-2 gallons a tankful out of Darryl's car. It's got my mileage up to 25mph and, I see, it dropped his mileage down a few mpg.

Is that wrong???

This way I can say my hybrid gets better mileage.

 

Only if you get caught!

 

Those guys are idiots. It doesn't take a rocket scientist to figure out a different way. Why don't they just give a new customer $80 cash at delivery instead and let him/her go fill the car up with premium gas. Or, better still, make the effort to do this service for the customer. That's what dealers in Canada do.

 

If your car doesn’t knock with low octane gas, you are wasting your money with premium. Octane rating is simply a measure of the gasoline’s resistance to detonation. It has nothing to do with the energy stored in the gas, or it’s cleaning properties. In fact, the compounds that are added to gasoline to raise its octane rating typically have less energy content than regular gasoline. I’ve run my LS460 almost exclusively on 86 octane gas from Costco. I’ve never ever had a knock or any other issues.

Daryll40 – I suspect the better mileage you got with 90+ octane gas over 87 octane was because a lighter wallet.

 

There is a knock sensor built into newer cars that retards the timing and power. I won't run my car on regular fuel.

Good luck,

Craig

 

Craig, Why not? Incase the knock sensor fails? I am interested in your perspective.

thanks

 

I'm not answering for Craig, but I'll tell you why I'm in agreement with him.

Forcing the knock sensor to retard your engine's timing by running low-octane fuel is just making the engine do something all the time that it was designed to do only occasionally. It's kind of like hitching a plow to a thoroughbred and asking him to run a race with it.

Over time, the retarded timing will likely cause accelerated deposits in the combustion chamber and on the valves and rings and plugs.

In short, it was designed to run on premium fuel and I personally wouldn't try to force it to run on anything less.

.
.

 

Mike, I agree with you 100%. We might ask Michael, One position what his take is on this subject. He's a Lexus Master Tech. I run the best fuel I can purchase around here, it's BP 93 Ultimate...

Craig

 

Mike_TX, all this assumes that the timing isn't adjusted properly to match the fuel. I see no evidence of this with my LS460 - I never get any hesitation or power loss, and my highway mileage is as good or better than the top figures posted on this site,
I would agree your points if the timing system over compensated by over retarding the timing. I am sure this is the case with many cars. If it were the case with my LS460, I would expect to take a significant power and mileage hit.

Bottom line, it’s no accident my car runs as well on regular as it does on premium, it was designed to adjust properly to the type of fuel being used.

 

I own a 1995 Infiniti Q45a. I have used regular (87 octane) gas for the last 10 years. It has had no effect on my gas mileage, and the loss of performance (while there) is not detectable without sophisticated testing insturments. The car has over 156,000 miles on it. It has run flawlessly. I have never done anything but routine maintenance.

My feeling is even if there are deposits, after 13 years, who cares. I changed the plugs at 90,000 miles. They looked so good I was tempted to put them back in and bring the new plugs back for a refund, but it wasn't worth my time, LOL!

I'm currently running 93 octane in my LS460, but I expect at some point I will switch over to 87 octane. I would expect this car to be even better at managing the lower octane, and the little extra power isn't something I need anyway.

BTW, its not that I can't afford 93 octane. Whatever the price of gas, it won't in any way affect my driving habits, its just that I HATE to spend any money I don't have to.