No its not going to have the same performance as the timing, boost is backed down...To get the best performance use premium fuel. One of my tunes is set up for regular fuel, I've never used it as the most performance is from using premium fuel....btw fuel is the cheapest part of operating a vehicle & a few additional dollars is worth the performance you get......

 

You can run 87, it won't void warranty. But you don't have the same performance. The 252 that the car is rated at is on 93. Or so the owner's manual says.

 

It will absolutely reduced power. 93 octane is what you need to get the rated power advertised by Ford.

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Yep lower the octane, lower the performance. For comparison you can look at dyno's from those in California or other states where the highest common gas is 91 octane and compare the numbers to even 93. It is noticeable.

87 is what the mpg ratings are based off though, so per Ford, you should be fine to use it. You'll just be down on the power.
EX, compare the ST vs a 340i vs Jeep Cherokee. The Ford says regular gas and the bimmer is premium (and i included the old ball Jeep since its one of a handful that requires midgrade!) https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=38477&id=37892&id=37852

 

I hate when I can only get 91. 93 all the way. Don't waste your time with 87 unless you are in a pinch.

 

I agree, I'm not sure what the dealership put in mine before I picked it up, so I'm trying to burn through it quickly so I can fill up with 93.

 

I have used 87 Shell gas in my ST. It is not any problem for normal driving. If you stay off boost you would never know any difference.
However if you run up to near redline I say stay away from 87. Yes the engine does cut back timing... etc. but the system is NOT happy with high revving and 87 gas.
I drive old lady 90% of the time. Sadly the ther 10% is insane banshee. I gave up totally on 87 since I disliked the hiccups at high RPM/WOT with 87 Worst when shifting gears at.near redline.
So I pay the $0.80 a gallon more for 93 all the time, just so when I DO boost.. The car just goes. No hiccups.. [angel]

 

my wife's escape, which has the same engine, only gets 87. its never had an issue, and nobody ever notices the drop of 10hp (or whatever it is).

saves 12% on my fuel bill.

however if you are frequently using high hp, like racing, or towing, or mountainous passes, then maybe higher octane can work for you to reduce knock.

it will to high/low octane almost instantly, so you can run 87 all the time, and then just before you do some performance driving, put a tank of high test in.