There is no shortage of misinformation.
All gasoline is the same. In fact it all flows through the same pipeline. What changes is the detergent package added by the supplier before it is delivered to the retailer-the gas station.
Octane is a measure of the gasoline's ability to resist knocking. Knocking is when the gasoline is already developing pressure as the piston is still coming up. Obviously that will damage the engine.
A modern car will have a knock sensor and will retard the timing, when the spark plug fires if the fuel is causing knock. This will reduce power and thus use more fuel per mile.
People who purchase fuel at places like Walmart, Costco truth is you do not know what you are buying.
High octane fuels tend to also be higher detergent fuels. Depends on what you are driving. A turbo, a supercharger may well require high octane fuels. Often they will suggest brand names.
Your golf cart, it is MY OPINION a waste of money.

Taken from owners manual for 2020 Yamaha quiet tech golf cart
 

Taken from our owners manual
“ Recommended fuel:
Unleaded gasoline
Fuel tank capacity:
22.0 L (5.8 US gal)
Gasoline-based fuels containing more than 10% ethanol are not recommended.‘

Ohiobuckeye
 

We had a 2018 & got 240 per tank of gas. My 2012, I only got 210 miles per tank, also I had 26,000 miles on it when I traded it for my 2018 & never had a single issue with my 2012. 53 mpg is great, thanks for sharing!

When we first started renting here - i was surprised how little gas we used in the golf cart. We rented around LSL - and mostly drove to/from LSL.

After we bought (near Brownwood) - all of a sudden we are driving to BW, some nights to LSL - and now to Ednas or Fenney Grill. We are using more gas each week.

Yep. I generally recommend that people RTFM. Lots of good information to dispel urban myths.

We have a 2017 Yamaha Quietech Drive 2, which gets 87 octane gas. I have installed a GPS based odometer/speedometer (eliminates the tire size problems) and we are currently getting 42 MPG on the first 4 tank fill ups.

There is one on Wedgewood Lane in Buffalo Ridge Plaza. It is in strip with Home Goods, Marshall’s, Beall’s, and Pet Store. Across from Fresh Market.

What is recreational gas.?)

That's the gas you get when you drink too much beer. :a040:

There is one in the Buffalo Ridge Shopping Center and one through the GC gate in historic section over by Walmart on 441.

This is gas that does NOT contain ethanol, in general meant for recreational vehicles that do not tolerate 'regular' gas used in cars. Now having said that most if not all of the newer golf carts (and probably other gasoline powered equipment) is designed for 'regular' gas, commonly up to 10% ethanol.

Go by Lowes and Aldi and take the path to Walmart and then Dollar Tree.

Is that about 3 rounds a day?

Costco gas is "Top Tier" gas. Google "Top Tier" to understand. So I take exception to your opinion that Costco gas is questionable.

Over 1050 on executive courses and around 50 on championship courses.
I played as many as 11 execs in one day(in light rain when no one else was playing) and 17 that weekend. I played as a single on most of the courses and a few with my friends when there was an opening. It was usually easy getting 4 or 5 rounds a day in.I met a lot of great people and TV golf staff.
On December the 11th(2020) Jeff Shain of the Daily Sun did a great article on me on the front page of the sports section.
Needless to say, I put a lot of miles on my cart and went through a lot of premium gas.
:):)