70monte

I always run Premium in my 14 GT. My last car required Premium so I'm used to buying it.

Wayne

jhawkr

I use about 600 gallons a year, similar to your use. If I use regular for 2/3 of the year, that would be 400 * .25 = $100/yr. Over 5 years that's $500, provided the price differential remains the same. $500 = $500 and with inflation no doubt to be factored in,
$500 > Future $500. It all adds up and counts toward your bottom line. $14 a month doesn't sound like much but $14 a week for 5-10-20 years should get ones attention.

audioAl

Almost 100 hp increase, the DOHC 3.7 has variable timing and can tell the octane and adjust itself, from 305 to 315 hp.

RetiredSFC 97

I might try premium in my 3.7 to see if I get a MPG increase. In all of my past cars if I used premium I did get a MPG increase. I had to use premium in my Cadillac and I used to complain about it, but reality it was only a couple more bucks a fill up and the car liked it better.

I agree with the person who explained recommended versus required. The cars will self adjust to whatever fuel you use but will get the optimum performance with the higher octane.

I don't even think a tune is all that necessary. The car will adjust itself.

dcarlinf1

My thoughts exactly. One should not buy a Mustang in the first place if you are concerned about fuel costs. Your driving style will make a bigger difference to MPG than the octane rating you buy. I could get 25MPG if I babied my 5.0 around town. But I don't, so I get about 18MPG on average. Drive it like you stole it.

So_Cali

Premium in my tank ALL the time. PERIOD. Every extra pony matters IMO. You gotta pay to play

Derf00

That is my point exactly.....

In the greater scheme of things and overall cost of ownership, $500 is a drop in the bucket. Insurance, tires, and performance mods (which we all do with these cars) are a far greater contributors to the cost of ownership.

Again, I guess to some that extra $14 matters...and again...you should be looking elsewhere IMO.

Derf00

It only works backwards... In other words, if the car says recommended 91 octane then you can use any grade you want.

If it states recommended 87 (or nothing about premium fuels) then to use a higher octane will not net any gains. Just a lighter wallet

The only exception is an aging engine where you have carbon deposits. Higher octane will help against pinging.

BrazenStang

I knew you'd be around here! I agree 100%!

If I was concerned about saving a buck I guess I would have read the 'recommended' fuel grade. I always run 93, and have a tune.

On the contrary. The car will adjust itself a little bit, but to truly see/feel performance gains you need a tune. I know from experience that the 5.0 has a lot left on the table in stock form. I would suspect that the 3.7 is no different.

To the person who asked about a difference in 3.7 vs. 5.0. The difference is huge! It takes a lot of $$$ to match the stock HP of the 5.0 with the 3.7. If you can afford the car, it is well worth the little bit of extra dough to buy premium fuel. And don't complain when you don't get 30 mpg, mileage is significantly lower.

jhawkr

Says you. Watching your money is a positive attribute and you will learn that someday. Or you won't and you will end up with nothing. $500/yr for 10 years is $5000. If you can save that money, and you are not using the full potential of your car anyway, why waste the money? I drive a Mustang because I like Mustangs. I've owned a 66, a 67, a 2010GT and the current 2014GT. (I wanted the last of the generation). And, I can afford it. I just choose not to spend money unnecessarily.