Midwest Gasoline to Spike $0.50-$1.00 Per gallon

[goeduck]

Time to bring back the Cash for Clunkers program or release oil from the oil resserves..... Oh wait!

The best price in my County according to Gasbuddy.com is $4.65 a gallon.

 

[Snobdds]

That is not at all how you do it.

If you're saying that a value decreased by 75% then what you have is:

123 (original value)
75% of 123 = 92.25 (123 * .75) (reduction amount)
123 - 92.25 = 30.75 (final value)

So the equation looks like:

V1 - (V1*.75) = V2

The way to find how much of a percentage of a reduction there is between two numbers is:

New value
------------
Old value

70.9/123 = 57.14xx% reduction

No no no no no no no

There is a huge difference between

% change

and

% of.

Moss did the same mistake.

 

[BigBlue1]

No no no no no no no

There is a huge difference between

% change

and

% of.

Moss did the same mistake.

If you say "An original value changed by 75% to a new value" then 75% is the portion of the original value that was removed. 75% of 123 is the amount reduced. There's no other way to look at it.

 

[Snobdds]

you're right.

Good luck.

 

[BigBlue1]

One more time...

If something goes from 123 to 70, how is that expressed in as a % change?

Well...

(123-70)/70 = 75% (I already did the x100 to express as a % for mr. bnold's hang-up). The price went down 75%.

We can check that number to make sure. To check you can do it two ways:

From the starting point of 70: 70*1.75 = 123
From the ending point of 123: 123/1.75 = 70

I hope you can see the multiplicative relationship here. It dosen't matter where starting point is, the relative ratio works either way. I explained earlier how to add (multiply) and subtract (divide) to keep the % change a constant ratio between two points.

I really have no other idea how to make you understand.

Here is where you demonstrate your mistake. Look at the formula in the second picture bnold posts in post 51. It is:

(New value) - (Old value)
------------------------- = % change
(Old Value)

What you list above has the original/final numbers backwards in the formula. Your 75% would be valid as the percentage of change IF the STARTING number were 70 and the ending number was 123.

This is for a starting number of 123 and an ending number of 70:

(70-123)/123 = -43.xx%, or a 43.xx% decrease

 

[Torvy]

Ouch. But at only a 7% surcharge for premium, that choice becomes easier. Most people can see 5-10% mpg improvement on premium, plus your engine just runs nicer overall. Unless you drive a turd that doesn't care, of course.

I used to think that, too. My oldest is a chemical engineer. He schooled me on why this isn't the case. At the time, wife drove an A6 (requires 'Premium'.) Apparently, the engine needs to be engineered or tuned to run on that octane range. I cannot explain the science, but he did. It was over my head. If the engine isn't made for it, you are just throwing away extra cash. I tried it with my '06 Prius. It got worse mileage with Premuim.

I suppose it is like horses. They don't run well on Premium alfalfa. Cows handle it just fine.

 

[mrmikey]

Fella I used to work with was complaining one day about the price of premium fuel. He stated that's it's better for your car and you get better mileage to which I replied BS. I've always tracked my mileage per tank on any vehicle I owned so I told him for the next four tanks I'll use premium fuel, I think at the time it was a Nissan Frontier 4.0L.
I filled up at at the same station by work, same pump and let the nozzle click off..no goosing it. I got the exact same mileage, no discernable improvement in performance, only thing changed was my wallet was a bit lighter.
Saying that, I used to buy premium for my small engines when they didn't put that corn crap in it but that had nothing to do with the octane for me buying it. Now corn crap is in everything unfortunately.

 

[Gale Hawkins]

I heard today at the federal level there is interest in a reprogramming cars to get better mileage if they're burning premium.

 

[Chewwy]

I heard today at the federal level there is interest in a reprogramming cars to get better mileage if they're burning premium.

If the Feds are involved it is likely FUBAR.

 

[BravoXray]

Fella I used to work with was complaining one day about the price of premium fuel. He stated that's it's better for your car and you get better mileage to which I replied BS. I've always tracked my mileage per tank on any vehicle I owned so I told him for the next four tanks I'll use premium fuel, I think at the time it was a Nissan Frontier 4.0L.
I filled up at at the same station by work, same pump and let the nozzle click off..no goosing it. I got the exact same mileage, no discernable improvement in performance, only thing changed was my wallet was a bit lighter.
Saying that, I used to buy premium for my small engines when they didn't put that corn crap in it but that had nothing to do with the octane for me buying it. Now corn crap is in everything unfortunately.

Regular and prmium gas are the same except for the additive to raise the octane rating. Both have identical BTUs per gallon.
That's been debunked a thousand times.
Premium is meant for turbocharged or high compression engines to prevent detonation.