No, it's not more than 2 mpg. It is between 1 and 2 mpg. And that is quantified on freeway trips. I'm not sure I can prove it in suburban daily driving.

The first time I heard of Top Tier was when my wife was reading aloud from the manual for her (then) new 2015 Hyundai Elantra. I had never heard of it. Lexus has subsequently jumped aboard the Top Tier train. I think it is probably worth a couple cents if you plan to keep the car more than 5 years. https://www.consumerreports.org/car-...h-extra-price/

 

Car and Driver did a comparison test a while back running cars on octane fuel that was different than recommended to see if it impacted HP and MPG. Long story short, "it depends". All cars tested that recommended premium but ran regular saw a drop in hp - like 1-5. Nothing any tester actually noticed driving the car. MPG was all over the place. Some got a bit less, some even got a bit more.

The RX will run well on either. The engine protects from knocking on regular octane by adjusting the timing and fuel. I read that most modern engines basically start up and have the means to figure out what you are running and just adjust accordingly.

All that being said, I'd simply recommend you try both (regular and premium) and see which you like better and whether the cost is an issue. Go with what your butt and your wallet find agreeable.

I'll offer that recently I found a gas station that has a "no ethanol" gas (E0 I think). Nearly all gas in WA state is E10 (10%). When I tried E0 (also 92 octane), I noticed an immediate boost in MPG (about 2 MPG). I have a 450h. For the distances I drive per month and given I get 30-32 MPG the cost difference between 87 and 92 was never large enough to make a huge difference - also in my car I do notice a small drop in MPG on 87. So I've just rolled with 92 and I'm happy. Now that I have E0 available, I'll be using that from now on.

 

Yep, I understand the marketed difference and benefit of Top Tier fuel. I just wonder if what we buy actually delivers the marketed benefits.

 

Good link. CR, at least thinks there is a difference. I wonder if their tests were run only on direct-injected engines and if the same benefit would accrue to port-injected or those that are both port and direct injected?

Apparently buying a "top tier" brand may not be enough. That's what I infer from this, "Check the licensed brand list. If the brand of gasoline or diesel on the signage or the dispensing pump is not listed, the fuel is not TOP TIER™. If a retailer is on the brands list but a TOP TIER™ logo isn't displayed at the station, please contact us." at https://toptiergas.com/how_do_you_know/. I'll be paying a lot more attention now....

 

In my area, the brands that are certified Top Tier all show it on their pumps: Shell, Costco, Exxon. Not Speedway.

 

Got it - I drove by the local Costco today out of curiosity and we're the same in Toronto 87/91.

I don't know about where you guys are, but Costco pricing demolishes the competition here - we're talking anywhere from 5-10 cents cheaper per gallon than Shell, Esso, Petro Canada - all the big names. It's no wonder the lines are so long.

 

I wasn't aware that Costco carries Top Tier until this thread. Even though I don't have one close to where I live.
Don't you have to be a member to purchase gas there?

 

I think so.

 

Yes, you do. But the lowest level of membership is only $50 or $60 per year. You can easily save more than that if you do some grocery shopping or buy household goods, plants, etc.

 

Prices today (9 OCT 2020) in my zip code (south Dayton, Ohio suburbs):

Costco: $1,82 Reg., $2.23 Prem. (this is the 91 octane)

Shell: $1.96 Reg., $2.53 Midgrade (this is the 89 octane)

 

All you need is a debit card or any VISA card. Membership is NOT required at Costco to purchase gas. Membership is only required if you want to enter the brick and mortar store.

 

Hmmmm. So, when the first screen on the pump says "Insert Membership Card", you do what, to get the second screen to come up, where it says "Insert Payment Card?"

 

Good to know.
Thank for the info.....

 

Unless it's specific to the Costco in your area, all the Costco gas pumps I've been to has a big sign out front that specifically says "Members Only". Sure, it can take any VISA card as payment (USA, or Mastercard in Canada), but you'll still need to scan your membership card first before the pumps will activate.

The only Costco area that is not member-specific used to be the food court area; so you could order the $1.50 hotdog even if you're not a member.

Edit: Costco Gas FAQ:

Q: Can anyone buy fuel at a Costco Gas Station?

A: The fuel station is open to Costco members only. There is an exception: Costco Shop Card customers do not need to be Costco members.

 

I must admit, this is the first time I am reading about this. I have been to several Costco gas stations and never have I had to scan any membership card (I'm not a member!). I'll pay more attention when I go this week and maybe snap a few pictures. The more you know, thanks guys!