You don't need premium. Maybe.

[trollbait]

That was my experience in the turbocharged Sonic. Improvement in fuel economy, but not enough for the price. Mixing my own midgrade from regular and premium would have equaled out in the price per mile, but I deemed it not worth the hassle.

A modern car runs just on the edge of knocking by continously adjusting the ignition timing in order to get the best performance and fuel economy. When a regular octane car runs on higher octane fuel, the timing advances as far as it can, which isn't far enough to get near knocking. That is why it may seem to run smoother.

[JockoT]

I set my ScanGauge E to show ignition timing, and today I was able to see that cruising at 50 - 60 mph with a light throttle results in an advance of between 30° and 36°. Now I have nothing to go by on straight 95 RON but when I change back I will see what the numbers are then, and report back here.

[gregsfc]

Evidently in N. America, the fuel refiners have more lobbying power than the automakers and truck manufacturers and off-road engine manufacturers, and environmentalists all put together. In the early part of the millennium, it took all the trucking industry and all the engine manufacturers begging and pleading and lobbying for years just to get ultra-low sulfur diesel as the standard diesel fuel here in the States and probably Canada too. And at that time the industry was up against it. The fuel neutral standard was about to begin that would have ended the diesel engine for on-road vehicles on our continent minus Mexico, and that would have basically destroyed our economy, because it would have put our transportation system at a huge disadvantage compared to the rest of the world. It took that level of a crises just to get a diesel fuel standard that pretty much all of the rest of the industrialized world already had.

Nowadays, engine manufacturers want 90 octane as the standard gasoline fuel in the U.S., so that basically we can all get modern engines without modifying them all to accept a lower-quality U.S./Canadian fuel, but it doesn't seem like it's going to happen any time soon.

This whole octane thing in the U.S. is a great big sham and uneducated and unsophisticated consumers allow this sham to continue. The mid-grade stuff (89) has always just been a product with no added value just to bring in more profit and revenue for the refiners as it has no place in our fleets. What should really happen in a capitalistic economy with educated consumers is that 89 should be moved up to 90, and then that should be our regular gasoline; then we'd still have the 93 octane for the few cars that run better on a higher octane. But even the premium stuff is mostly a sham. Some fuel refining companies add extra detergent in the 92-93 stuff and leave an inferior amount of detergent in the other so-called grades of gasoline, as the standard for the detergent level over here is lower than what engine manufacturers recommend. The fuel and petroleum industries basically run a cartel over here and every other industry has to work around whatever crap they decide to sell us.

[Airstreamer67]

My 2015 Mazda runs on regular gas even though it has a compression ratio of 13:1. I'm glad, because the price of regular unleaded in the US continues to be amazingly low.

Yesterday, I paid $2.36 a gallon, which is a noticeable saving over the cost of premium and that of diesel, which has been running 30-to-50 cents more per gallon. Fuelly shows that my lifetime average cost per gallon is just over $2.00, which allows for a cost-per-mile of 4.5 cents.

All this is not bad for a 3000-pound car with automatic transmission. My car so far has a lifetime fuel average of over 44 mpg due to its being operated mostly on the highway and relatively little in the city. However, I live in Louisiana with lots of heat and humidity, so the air condition is on almost 100% of the time.

[JockoT]

Wow. I currently pay $7.38 a gallon. Okay, our Imperial gallons are a bit bigger than US gallons, but not that much bigger!

[trollbait]

Originally Posted by Airstreamer67

My 2015 Mazda runs on regular gas even though it has a compression ratio of 13:1. I'm glad, because the price of regular unleaded in the US continues to be amazingly low.

Yesterday, I paid $2.36 a gallon, which is a noticeable saving over the cost of premium and that of diesel, which has been running 30-to-50 cents more per gallon. Fuelly shows that my lifetime average cost per gallon is just over $2.00, which allows for a cost-per-mile of 4.5 cents.

All this is not bad for a 3000-pound car with automatic transmission. My car so far has a lifetime fuel average of over 44 mpg due to its being operated mostly on the highway and relatively little in the city. However, I live in Louisiana with lots of heat and humidity, so the air condition is on almost 100% of the time.

That Mazda, and many other brands, has direct injection. These engines can run at higher compression than a port injected one on the same fuel. The higher compression then allows better performance and fuel economy.

Going back to other countries having better fuel. That engine in those markets has a 14:1 ratio.

[Draigflag]

Originally Posted by trollbait

That Mazda, and many other brands, has direct injection. These engines can run at higher compression than a port injected one on the same fuel. The higher compression then allows better performance and fuel economy.

Going back to other countries having better fuel. That engine in those markets has a 14:1 ratio.

Better performance and economy at the expense of emissions. So many cars taken off sale because of the particulate matter now whilst they adapt them with GPFs (gasoline particulate filters)

[Draigflag]

Er....yea $8.27 a UK gallon for premium I just filled up, cost the equivalent of $92.88. Feel slightly sick, fuels not been this expensive for years, I can't even remember when....