I have done enough reading about that subject to make my eyes bleed. There are all kinds of factors involved. I did find it interesting that octane ratings used are different in the USA than in Europe. We use the average of the Research Method and the Motor Method. Europe only uses one of them (Research Method?) that gives a higher number. If you look at a gas pump in the USA, they have the yellow sticker with 87, 90 or 93 on it.........and they have (R+M)/2 at the bottom of it. That's why what is 95 octane in Germany is 90 octane in the States. Likewise, the 98 octane over there is equivalent to 93 here. If they sold what we call 87 octane regular in the EU, it would be called 92 there.

From what I have been told by German car folks I met, they run smaller engines with higher compression ratios - many of them turbocharged; and they need a bit of "oomph" for Autobahn driving. We had to buy our gasoline at Esso (known as Exxon in the USA) because we got a substantial discount through our AAFES debit card. If fuel was 1.85 Euros per liter, our AAFES price was about $1.15 per liter. Germans paid about $7 per gallon and we paid about $4.20 or so, but it did fluctuate up and down a bit while we were there. We had to calculate liters to gallons and Euros to dollars.........lots of fun.

At Esso stations, their cheapest fuel was called Super 95 E10 - gasoline with 10 percent ethanol. They also had Super 95 E5 available (what we always bought) with 5 percent ethanol, for a few cents more. The Super+ 98 premium was always E5. I know that some stations sold ethanol-free gasoline and both Shell & ARAL stations offered a Super+ 102 blend; but we never had any need for that with our car. That would push one over the eight dollars per gallon threshold. Ack!! I never noticed any mid-grade gasoline in Europe. You also had to pump your gas and THEN go inside and pay. No pay-at-the-pump options for us. I hated that.

When I was in Denver years ago, I noticed that the octane ratings were lower - 85 octane was regular, 87 was mid-grade and 90 was their super. Obviously, it had something to do with the altitude and the thinner density of the air. I only had a rented Nissan Sentra, so I couldn't tell anything about performance. That little Sentra did make it up to the top of Pike's Peak, though. The altitude was 14,000 feet. My son and I went up there when we were on vacation out there. Try running 100 meters from the parking lot to the gift shop. You run out of steam very quickly with that thin air. Haha!!

A big marketing tool of gasoline stations is the "Top Tier Fuels" thing. All gasolines in any area are pretty much the same, but they use certain additives that are claimed to be helpful. I generally go to Exxon or Shell - both are "Top Tier" gasolines.........but it is mostly because they are closest to where we live. Sometimes I top off at Sheetz or Wawa if I happen to need fuel - as they are competitive on price. Costco is almost always lower than anybody (and is a Top Tier brand), but it's on the other side of town and not worth it unless I go there for something else.

 

All that reading and eye bleeding and you missed a couple of BIG things?
The ratings are not guaranteed and even all states do regular testing to make sure gas stations are in compliance the reports indicate often times the tanks do not have the exact octane they are Federally required to have sticker on the pumps in plain sight for the consumer. The cause is often related to old gas or a dilution of gas that was accidently introduced during the filling. Most never know this happens and fill their tanks and happily go on their way. It's not a big deal unless you have a modified engine that absolutely requires a specific octane to run.
As for the term "TOP TIER" that was always for advertising gimmick and really is meaningless. And the part that all refine petroleum into gas are the same is also inaccurate. While there are better suppliers that offer improved formulas and also cost more as well in the long run are better is so many ways for the engine and environment we still get the other station that not only do not have that better formulas but buy from several gas wholesalers , going outside and using other than the better branded suppliers of gasoline you really never know in the end what is going into your tank only in part the hope that the Federal rating sticker on the pump is being complied with for at least the octane rating.

I prefer Cheron and Shell there are a couple others but these two I absolutely know that any retail gas station with the Chevron or Shell colors and signage must comply with a contract that they cannot sell anything in their pumps except and from Shell and Chevron fuel wholesale distributors. This is not the case with many other gasses station even the more popular ones. The only way is you would have to ask them. Good luck with that getting an answer and that answer your can trust?.

The WORST thing anyone can do is compare US and CANADA fuel to any other country in the world. But that is a BIG subject, and I am not interested because I don't live there. But DONT try to compare do your "Due diligence" in fact finding and Good luck with finding empirical fact about that. LOL
I might also add many other countries have no laws or checks and balances for compliances as to what they "must" sell .in their storage tanks at retail gas stations. Also, there are thousands of gas stations worldwide that still use non plastic storage tanks, and many storage tanks are over 50 years old in some countries. Gotta wonder what all that addition "stuff" is going into your gas tank from them? lol
I bet some are thinking why would anyone care so much about the gas. Well for me it's simple... I know what not buying from Chevron (has other brands associated with Chevron) ,Shell Union *76 (*only some stations) gas will eventually do to an engine. And the biggest reason that some of my professional racing it is imperative that I use the exact octane of fuel and i test for at least the specific gravity when I use it. So, I must believe that the octane rating and how it was derived is absolutely accurate.

 

It's easy to get into the weeds with the subject of gasoline. In our county, they sell a typical "Virginia" blend of gasoline. If I go two miles to the west, they require a different 'boutique' blend be sold. Richmond has yet another standard for the city and the surrounding counties. Petersburg and Colonial Heights are always a few cents cheaper because they don't have to sell the same blend and it's apparently less costly. The octane is pretty much standard in our area - 87 for regular, 89 or 90 for mid-grade and 92 or 93 for premium. Some stations sell E15 blends that are 88 octane and a handful sell E85 that is only to be used in "Flex Fuel" rated vehicles. ( The higher ethanol content gasolines are a bit cheaper at the pump, but your fuel economy takes a dive. Ethanol has a lower BTU content than gasoline, so there's less "energy" in a gallon.

I do notice that the same tanker trucks will visit stations with different brand names. Makes me wonder about the consistency fo the fuel. Most all of the tanker trucks fill up at the same 'tank farm' with the gasoline & diesel being pumped from the same refineries. I always wondered if it was bad luck to get gasoline while a tanker truck is delivering. Perhaps the fuel flowing into the underground tank will 'stir up' sentiment on the bottom of the tank. In 45 years of driving, I've never had a fuel issue in any of my cars.

When I drove tractor-trailers, I once had a problem almost two decades ago when the tanker driver accidentally put unleaded gasoline in the underground diesel tank. We had a few trucks that broke down because of it. I had only topped off, so I still had 175 gallons of diesel + about 25 gallons of contaminated diesel/gasoline blended in. My boss called me and I merely topped off with good diesel at the nearest station. It seemed as if my rig was running a little weird, but I got through the day without it dying on me. We had four or five drivers who had to be towed because of it! A Cummins or Detroit Diesel engine doesn't run very well on gasoline.

My wife and I used to have Corvettes and they definitely needed premium fuel. Our Mazda CX-30, our Honda CR-V and our F-150 all run fine on unleaded regular. Some older cars, though, really don't like ethanol-laced gas.

 

Just a couple things for me to make comment on,

I live in California (IMHO run by a dictator) that say pretty much everything about gas. Highest tax highest control of emission standards pretty much the highest price per gallon nation wide. Yesterday Chevron in my town where I always fuel up was 5.96 per gal.

Yes I remember the days when there were frequent mistakes made lead and un-lead gas mix-ups

Federally mandated replacement nationwide of old metal tanks to new plastic prevent sediment and prolongs the gasolines life .

The Corvettes did not always need Super (as it was called) because no all had high compression engines. That was always a Myth.

I bet you remember the gas lines ? Even /odd days for filling (depending on your license plate) and no more than 10-15 gallons at one time ?

 

I am familiar with some of the goings on in California. My stepsister lives in Orange County. Prices for everything out there are insane! $5.96 is outrageous, almost to the point of what fuel costs in Germany - about seven bucks a gallon. In my part of Virginia, unleaded regular runs about $2.99 to about $3.15 per gallon as of Thursday.

I grew up when gasoline had lead in it and then the unleaded fuel was gradually phased in. Most cars made for 1975 and later had catalytic converters that necessitated using unleaded fuel. The filling stations had smaller nozzles for cars that ran on unleaded. A hose from a pump dispensing leaded fuel would not fit into the fuel tank of a car made to run on lead-free gasoline. The lead would ruin the catalytic converter. The last gas station I remember with leaded fuel was in Pennsylvania back in 1988. I know you could probably find it for a few more years, but I never had the need for it. It's probably illegal to run leaded fuel in any car driven on a public road nowadays.

I once had a 1964 Cadillac that called for 96 octane leaded premium. HAHA!! Not easy to find in the early 1980s. The only gasoline that ran decently was the Sunoco (Ultra?) that was dispensed from their dial-a-pump. I think it was 94 octane and it actually had a greenish tint to it. Stuff smelled really good too. You probably cannot even buy it today. None of it had any ethanol back then, either. I later had a beautiful 1978 Oldsmobile Ninety-Eight and - as was the case with the Caddy - the fuel filler was behind the license plate. No worries about parking one the proper side of the pump. I sort of miss that - even though it probably was not as safe as modern cars with the filler doors on the side of the vehicle.

I never gave it much thought to the material used to build the underground storage tanks, but it makes sense that they not be always made of metal. Less issue with rust or corrosion - let alone leakage into the environment. As far as I am aware, they bury them in some kind of hard clay & soil mix to help contain any leakage. Modern gas stations also have more safety requirements - including overhead fire extinguishers, breakaway hoses, insulated/grounded lines, etc.

Different Corvettes require various grades of fuel. Many of the ones from the 1970s probably can run on regular pump gasoline. If you get one of the brutish 427 big-block models with high-compression pistons and have the timing set kind of far ahead, you won't do very well running 87 octane unleaded. I had a 2017 and my wife had a 2019 with the 460 hp 6.2L small-block V8. They were set up to run on premium unleaded gasoline, but the owner's manual said that you COULD run 87 octane if that was the only gasoline available. Obviously, we always ran 93 octane premium in both of them - even though we never tracked or raced them. I never tried running 87 in either of them. A modern fuel-injected Corvette with 460 ponies on tap needs more octane than a 1979 Corvette equipped with a mild 350 that wheezed through a small carburetor and put out just 180 horses on a good day.

Gas lines? Oh - heck yes. Who can forget those? The first energy crisis was in 1973 or 1974 and we had a huge Caprice Estate wagon. My dad used to carry ten gallon gas cans when he went to fill up (we bought fuel on base) and then we got those ration tickets that only allowed you to buy a certain amount at selected stations. I was only 8 or 9 at the time, but have some memory of it. During the second energy crunch of 1979 and 1980, we lived in Pennsylvania and they had the odd-even rationing (depended upon your license plate number(). For a time, they had a $10 limit and some areas limited you to just $5 per trip. The old gas pumps only went to 99 cents, so some stations had to sell it by the half gallon - as in 55 cents for a half gallon rather than $1.10 for a full gallon, etc. My mom then traded in our beautiful Caprice wagon for a new 1980 Chevette. Ack!

You really jogged my memory there, sir!
.

 

My first car was in 1973 1966 Buick LeSabre 2 door hardtop. Driver license age 16 I started hobby drag racing in 1976 at Fremont Dragstrip in a 1965 Olds F85 Station wagon. Ran consistent 12s with a 330 . Back then a street car doing those times was very quick . This eventually grew into racing professionally NHRA 1980 -1995 . Naturally I was also a street racer and often cruised Friday and Saturday nights looking for some stoplight action. Fast forward (even today) on no emission engines now for the street I still use 100 octane leaded gas with a secret gas stabilizer that makes it valve safe Or I run straight xylene. I even run that with a few other engines occasionally even my 2019 2.5 Mazda.
Generally speaking I always found a way around the decline gasoline formulas.

 

Oh, wow! 1966 LeSabre? Olds F85? Now that goes back to a different era. Getting into the 12s with any street car is impressive...........especially with the tire technology back then.

100 octane leaded fuel? That sounds like aviation gasoline to me. Yikes! If you can even find it, that might cost a pretty penny.

 

Ansen sprints with Bluestreak tires.
I was actually older than the era I really liked which was axled front ends. I built my 1957 Corvette with a RAT 396 rock crusher 4 speed and an axled front end. And that was in 1977. I also built a 360 BB with dual carbs axled front end and a top loader. These were all street cars. My list goes on with about a dozen. Back then they were cheap and we all traded up between friends and just people we met.
Av gas is very regulated now however I have a pilot's license so when I go to the airport, I always bring a few 5 gallon gas jugs. The Federal regulation state you cannot put lead fuel directly into any vehcle other than an air plane but nothing about spare jugs. However I don't do that as much as I use to know with several of my vehicles like the Mazda I just upload a map specific for the fuel type and not worry about the engine crapping out a valve out the tailpipe or splitting a piston in two. lol

MY thought (back on topic) is even with a CX-30 if anyone is going to keep it for more than 5 years to at least explore the thoughts of getting an ECU calibration for the exact driving and driving condition you will be using it. You can improve most all aspect if it be better fuel economy or a bit more grunt power. If you choose a good company, then you can download your complete ECU as it is and then upload the adjusted one. Then whenever you need to go to the dealer or sell the Mazda you can upload the complete back OEM ECU program, and no one would be able to know that was done. The most it may show is a resent OEM "flash" which is perfectly legal and would not influence the remainder of the warranty.

to be clear I do not advocate the use of ECU/EFI Performance calibrating for removing control devices like a Catalytic converter or any system or part that would increase the emission standard set be the auto manufacture of any production vehcle. I should also point out that altering and or removing a CAT is a Felony and if you are caught on a federal lands/reservation (like a federal Park) with it altered or remove they will impound your vehcle and likely arrest and charge you with a felony.

 

I don't know what Ansen refers to (a type of car?), but I do remember Blue Streak tires. They were typically the choice for state police/highway patrol cars because they were good for high-speed driving. They also were very tough in regard to being puncture resistant, etc. It's amazing how far tire technology has advanced over the years, isn't it?

A big-block in a 1957 Corvette? Wow! That must have hauled ***. If memory serves me correctly, the first Corvette with a Mark IV 396 big-block was the 1965 model. A year or two later, the 427 was the big-block choice and was available in a few different horsepower ratings. A "rock crusher" was the Muncie four-speed, right? M-22 or something like that, I think. It was not unusual for shade tree mechanics to swap out engines or transmissions on a Saturday afternoon back in the day. Cars were easier to work on before all of the electronic wizardry and computerized systems took over. A friend of mine hand-built his 1969 Chevelle over the course of a few years - but that 427 ran like a scalded cat. He worked at an airport, so he was able to get AVGAS pretty easily back in the 1980s. Potent stuff for sure! ( I suppose many of the EPA regulations have severely limited its availability. )

Interesting idea about the ECU upgrade to the CX-30, but that's probably not necessary. It gets decent fuel economy and runs quite well. My wife drives it about 2/3 of the time and I am behind the wheel the other 1/3. She has a 40-minute commute each weekday, but often gets to work remotely form time to time. This week, she worked from home twice because of inclement weather. I understand about removing a catalytic converter being a big no no; especially since we have state safety inspections every year in Virginia. We don't have it in our area, but the folks in the DC suburbs - Fairfax, Alexandria, etc. - have to undergo emissions tests annually. The authorities don't play around with that kind of stuff. It amazes me that some folks will buy diesel pickup trucks and remove the emissions control devices (DPF, etc.); seemingly not concerned at all about getting caught.

 

I was challenged by my friends winner a case of beer, if I could pull the 4 cylinder out of one of my MGA's swap and American V-8 and have it turn key by Monday.I did not sleep for 2 1/2 days and won my case of beer.
However this got my to wanting to do a couple more MGA conversions. The last I did was a complete 391 small block BLOWN with Crower fuel injection. It looked like a Hot Wheels car. Less then 1500 lbs wet. I could haze the tires at 60+MPH. LOL Oh and there is pictures of it somewhere on this forum as well a few of my other *ODD RODs. lol
Ansen Sprints were a popular slotted wheel. (See American racing wheels) And you could get them in very wide sizes back on the 70's. I ran 15x10's. The Goodyear Indy Blue strikes "STOCK CAR" tires were classic Racing tires not really used on the street. They had the reputation when warmed up to give superior traction but at the expense of wearing very fast like 300 miles or less in perfect operating condition.