The trip computer said 25.1 and that was probably right since I was doing 75-80 when I wasn't in SJ/SF traffic.

I must say the car rides so smooth I could barely tell the tires were touching pavement on smooth patches of road...very pleased with the ride.

The car performed exactly like it did on premium and always responded as usual but I think going forward I'm going back to the original game plan and will feed it the premium it says it requires...my thinking is it's not worth the small increase in price to have peace of mind when I put my foot into it.

 

Thought to provide an update on my findings with regards to premium vs regular gas:

I ran regular gas for months and got 27 mpg consistently, sometimes high 26, but mostly low 27s. One thing I noticed was slower throttle response: e.g. when wanting to suddenly accelerate it would think (hesitate) for a split sec before actually accelerating.

Then I switched back to premium gas and ran it for a few weeks now. The mpg increased to mid 29s and has been consistently there. My driving route remained the same (50/50 hwy/city) and my habits too. The throttle response rate improved and now I can count on the car to accelerate when I step on it that very moment.

Overall: gas cost to me remained the same (+2% increase). The only benefit is the improved response rate, I would say likely due to advanced timing (difference from 87 to 91 octane)...

I will keep running premium as I like the engine response better now

Notes:
Cost: regular gas is currently at $1.17/liter and premium at $1.30/liter = increase of 11%
Gas consumption improvement of 2.5 mpg over 27 mpg = 9% improvement (reduction)
Net = 2% increase in cost

 

The difference is insignificant for the average driver. Lexus/Toyota rates the 3.5L engine at 272HP using premium or 268HP using regular. The use of regular became the choice of most due to the price of gas so they ended up derating the engine. As to gas mileage it isn't more then 1mpg so if you are on a freeway at 75mph you should be getting 31-32 mpg with either fuel type. City driving should be around 25-26 without to much effort. My overall mileage from the 1st day I purchased (new) the car is at 27.8 mpg. There is no performance difference and if you have a slight hesitation on start then my bet is you have a different issue coming.

 

Ahem, lets hope not!

The "hesitation" I am talking about is a slight throttle response delay when using regular gas vs virtually no delay with premium - during driving (not start). With regular gas the ECM will retard the timing (hence the different HP). It is a known fact that on a same engine, there is a difference (even so slight) in throttle response at different ignition angles. For example, if you put in regular into engine tuned for premium, it will get adjusted down by ~2 deg and there will be a response delay which most drivers won't feel or look for on 270 HP engine...

 

I think Igzy's test results are indeed significant. A 9% increase in MPG can not be compared to a 2% increase in overall cost. a 9% increase in mpg means a "Much Happier" car. That's why I've always said that each person needs to test for themselves what their car like best. In Igzy's case, his car definitely like the premium gas better. That means it is less likely to have as significant of engine issues in the future. That alone negates any question about the 2% increase in overall cost to operate.

And me personally, I didn't buy a Lexus with the thought of "Pinching Pennies". When I chose the Lexus over the Cadillac, did the 30+ MPG play a part in the decision over the 22 MPG of the Caddy? A little. But not enough when you consider the cost of both vehicles. If I really need to pinch pennies, I could have done that on a vehicle that costs a whole lot less. If saving a couple of dollars per month is more important to me than the car operating at it's peak performance and potential; then I would have bought a brand new 2014 Nissan Versa or Chevy Spark for $12,800 brand new.

But again; each car is different. Some cars reach their highest potential with 91 octane; while another may be at 89 or 87 octane. Igzy's test is conclusive enough to show that his car prefers premium gasoline. It performs better and gets better mileage. That's what he should be using. For me, at my gas prices, the difference in filling up my car between premium 91 octane and regular 85 octane (High altitude is allowed 85 octane), is about $6. $6.00 is well worth it for my car to run better. If the $6.00 is that important to a person; they probably shouldn't have spent as much money as they did on a Lexus. They could have saved $20K to $30K and bought a different car. If your car operates the same or better with 87-89 octane; then save the $6.00 per month. If your car operates better using 91 octane, then spend the extra $6.00. My car definitely performs better with 91 octane. Apparently so does Igzy's car.

 

What gas you use is a similar discussion as to what is the best oil to use. Everyone has an opinion and if a couple of dollars is worth it to some then so be it. The ES is a land cruiser and not a performance car. It is meant to be an upscale Toyota which provide a little more room and a smooth cushy ride. For the average joe and maybe the seasoned driver my bet is in a blind test they won't know the difference between regular and premium gas. So use what you want and enjoy that old man ride of comfort. If you want performance there are plenty of upscale 400+ HP sedans out there that give it to you . With performance you affect comfort and with comfort you hurt performance. There are some that share some what of both but most of them start at above $50K.
OK so what is the best oil to use????

 

That's a no brainer.

#1: Royal Purple
#2: Mobil 1 Extended performance

Then again; I STILL CHANGE OIL every 5,000 miles. Even with using Royal Purple or Mobil 1 Extended.

5qt Bottle at walmart comes out to about $7,50 a quart for Royal Purple and less than $6 a qt for mobil 1 extended performance. But like I said in the previous posts, I didn't buy a Lexus with "Price" in mind. I bought it because I like how it drives. Fast, Smooth, comfortable; and one of the most reliable/dependable cars. When I was younger and "Financially Challenged" (AKA Poor), I used the $2.00 a qt oil, or, if I used Mobil 1, I would take it to the 10,000 mile interval.

 

2010 Lexus Es350 , Castrol 5W-30 Dino oil every 5,000 miles , regular gas
2012 Jaguar XKR Convertible , Castrol 0W-20 Syntech every 5,000 miles , premium gas

Cost is not an issue as one is for local runs and one is for fun. In fact I'm just heading out to the club for a round of golf. Time for the fun car again. Enjoy your day.

 

Fun car

 

something that i found out on my drive out west to utah from Florida.
since i never drove out to the west coast before is one i hit NM and got out of texas i was no longer able to find 87 as a regular fuel grade regulare started to be 85 octane.
i don't understand how come the west coast can justrify 85 octane being regular.
i put that in my car and my MPG went down.
so i started to put 91 in my car and it went up.
I go to costco for fuel i live up ontop of the moutnain in Park City utah.
and i go to salt lake city once a week i stop at costco to fill up.
i would get mid grade but costco doesn't have midgrade just regular and primume.
another thing i don't understand is how come i can't find 93 here on the west coast