I have the 2008 lexus gs350 with 160k miles on it. I bought it 1000 miles back and never used any grade other than premium(93 costco). My mpg used to be 23 on highway and 18 in city.

Today, when i was driving i found the fuel is low and went to the nearest gas station and found there is no 91 and 93 octane. So, i filled up the tank with the 89 grade. Surprisingly, the mpg on highway is now 30.9. How in the world did this happen?

Someone explain!

 

Driving like a granny? jejeje

joking aside,,, don't waste ur $$ on expensive gas. Get the cheap stuff, it's fine.

MPG's are related more to cruising speed, city driving, how fast you accelerate, got a flat tyre? Consumer Reports equated the extra gas used by run the AC to the drag created by keeping a window open.

Regarding gas, make sure you get it at a Tier 1 stations; Chevron, Shell, Costco. Not at uncle Joe's station and u should be fine.

 

Is this actually truth? I’ve seen 50/50 split on the whole premium/regular gas debate... I had an 04 IS for 5-6 years and ALWAYS pumped her w 93. Now my 09 GS gets the same treatment.. I’ve heard stories of jumpy acceleration or poor mileage. And plus, if Toyota is recommending it, why should we go against it?

 

I’ve had 3 GS’s and each one has gotten better gas mileage with premium over regular, and even better mileage with non-ethanol 90, than with ethanol 91-93.

 

Manual recommends 91 octane but I have been feeding my car 87 the last 103k miles, now total miles including previous owner is 250k and the engine has not Blown up yet,