What do you fill your car with and why?
Does it really make a difference?
Only high compression engines require premium gas. The vast majority of cars won't benefit from high octane. Unless you drive a performance car you're wasting money. And if you do drive a performance engine you're also wasting money, because you are still only going from point a to b.
"And if you do drive a performance engine you're also wasting money, because you are still only going from point a to b." Everything can be considered a waste of money if you dumb it down that much. Playing video games is a waste of money because you paid to watch pixels on a screen. Tabletop gaming is a waste of money because you paid for miniatures or a core rulebook. As an enthusiast of cars, video games and tabletop games I think it's a little silly to call them wastes of money if you're not a hobbyist in that certain area. Some people simply enjoy a different feel for driving, in many cases a lot of us go on cruises or track days, making it our daily driver is hardly a stretch.
This much is true. My last three cars have been used Mercedes, they all require premium, and I always use regular. They love it. I had an organic chemistry prof that convinced me how inconsequential the difference is. I always use synthetic oil, however. If you are lazy about oil changes, it makes a big difference.
The Octane Rating of fuel references the fuel's resistance to burning. Contrary to common thinking, 87 octane gas is a lot more flammable than 110 octane racing fuel. "Resistance to burning" also means "resistance to knock" or, technically, "resistance to premature detonation." This becomes useful when compression ratios are higher. Compression ratios are higher because the efficiency of an Otto Cycle internal combustion engine increases with delta T (heat) and the more you compress something, the hotter it gets. At the extreme end, diesel engines run compression ratios an order of magnitude higher than your gas engine. You can drop a match in a jug of diesel and it will go out. Try it. Essentially, high octane fuel is necessary for high compression ratio engines which tend to be high efficiency, high performance engines. If your car's manual does not specify high-octane fuel, you do not need to use high-octane fuel UNLESS Using regular octane fuel causes your car to knock when you accelerate up hill. This means that carbon deposits within the combustion chambers of your engine have raised the compression ratio above design. On the plus side, you're getting more oomph. On the minus side, you're getting more heat. And you need to buy gas that doesn't cause knock. The manufacturer doesn't tell you to run 92+ for shits'n'giggles. They tell you to run 92+ because the engine is designed to run on 92+. If they tell you to run on 87 or better, run on 87. Or better if it starts knocking. And that's about all I have to say about that.
Diesel is less volatile, has less fumes. It is more like oil than gasoline is.
The guy down the street just got a Tesla model S. I've not met him yet, but I wouldn't mind a ride in it. I think the model S could eat that car :-)
I specifically bought a Subaru Legacy 3.6R over the GT because it only requires 87 octane. The turbo GT model would have needed premium and gotten less gas mileage, and only has slightly better HP/Torque. I always use regular. Only need higher octane gas for cars that require it, mainly supercharged and turbo boosted cars, or cars that have been "chipped" to burn the high octane gas appropriately.
The word "octane" has different meanings in different parts of the world. To understand how, you must first understand one of the physical properties of motor fuel. One of the checmicals found in your fuel is isooctane, and what it does is helps the fuel to resist self-combusting when it's compressed. As you probably know, your engine works by compressing the fuel, igniting it, and then using the resulting "explosion" to push the piston back again and drive the crankshaft (in turn, in most engines that we're concerned with, this drives a piston to compress fuel in a different piston or pistons). Now gasoline's reasonably volatile, and if you compress it hard enough, it ignites all by itself: but isooctane helps to prevent that, allowing it to be compressed further without igniting. There are a variety of different ways to measure how much isooctane is in a fuel, but they all boil down to basically the same thing: you put the fuel into a test engine that can vary the amount of compression it applies, and start burning it, gradually increasing the compression until the engine starts "knocking" (also known as "pinging"). This is what happens when fuel ignites prematurely, as a result of being compressed (i.e. before the spark plug fires), and it's not good for the engine nor for fuel efficiency. By measuring the pressure at which this happens, you can calculate the Research Octane Number (RON). Higher RON = more resistance to compression. If you drive anywhere in Europe or Australia, the number you're seeing (e.g. 95, 97) is the RON of the fuel. Another way to measure the octane of a fuel is the Motor Octane Number (MON). This uses a different kind of test engine that proponents claim gives a better representation of the way that the fuel behaves under real-world conditions: at a higher temperature, faster engine speed, etc. The MON is always lower than the RON, usually by about 8-10 points (but exactly how much varies). In many countries with ratings for fuel, a fuel must meet a minimum rating of both RON and MON in order to be classified as "premium", but legislation varies. When you drive in the US, though, what you're seeing is the Anti-Knock Index (AKI) (or Pump Octane Number). This is simply the mean average of the MON and the RON of the fuel. So broadly-speaking, a European 95 is about the same as a US 89, and a European 97 is pretty close to a US 93. You should always use the fuel that your car manufacturer recommends. And here's why: if your car recommends regular fuel, but you put in premium fuel, it will have no appreciable effect whatsoever: the fuel gets compressed just the same, and is ignited by the spark plug just the same, and then provides the same amount of "push". In other words: premium fuel in a regular car is a waste of money. The other way around is even worse: a premium-fuel car is tuned to compress the fuel more than a regular-fuel car. But when you put regular fuel in a premium car, there's a risk that the fuel will auto-ignite in the piston prematurely (i.e. before the right point in the stroke). This means that the "explosion" pushes backwards against the movement of the crankshaft - known as "pinging" for the noise that it makes. Using regular fuel in a premium-fuel car lowers fuel-efficiency and increases wear on the engine. Many modern premium-fuel cars with engine management computers can compensate for using the "wrong" fuel by adjusting the ignition time, but it'd still be better if you just put the right fuel in it to begin with. That's a little bit of a simplification, but it's broadly what you need to know.
Yeah, but I don't think it does anything beneficial for your car at all to upgrade to "middle". Especially if you only do so occasionally. Better to keep the extra money and buy a pop-tart.
Bummer. I think it's a shame people don't keep their cars past 100k miles. Buying a new one with that frequency is unnecessary consumption in my opinion. As long as you take care of it, it will go for twice that without a problem. My VW has 210k on the clock and is 21 years old. Still works fine.
I've got an '05 with 138k on it right now. Plan on driving it until repair costs start equalling a monthly payment. I absolutely love not having a car payment. Unfortunately, living in the Midwest with salted winter roads has done a number on the body. I've got some rust around the wheel-well that is only going to get much worse. I predict that in a couple of years I'll be torn between the enjoyment I get driving cars as long as possible and just being embarrassed to be seen in it. I don't need amenities in my car, but if it looks like garbage...I don't know if I could take that honestly.