MikeMS3,
The MSSP3's engine has been "tuned" for optimal performance using 91 Octane fuel. You can get away withlower octane (down to 87) in a bind, but it will reduce performance. In theory, if you are using 93 you may beactually reducing performance slightly, as well --The higher the Octane, the slower the "burn" - and if the engine is "tuned" for 91,93 canincrementallyde-optimize the ignition timing coordination. Plus you're paying more $$'s than you need to.Owner's manualP.4-2 calls for 91.

Your commute is likely the cause of your MPG. I drive approx. 50 miles each way to work - 95% on the interstate. When I drive "liberally" and apply occasional bursts of power along the way, I have measured 22-23MPG. As an experiment -- and a very difficult one to constrain myself towith 263 ponies under the hood -- I have tried to drive my MSSP3 like a "baby", cruising along at 60 mph and avoiding bursts of power. I have measured 26.5-27.5 MPG in those cases.

Not a bad deal - 263BHP, one of the fastest production cars in it's class -- sticker of only$23K -- and upto 27 MPG fuel economy... Zoom Zoom.

 

I only have about 2k miles on my car, but I am averaging a little more than 24 mpg. Most of my trips are in the 10 mile or less range. I plan to take a cruise to the mountains this weekend, and so I expect my average to increase a bit.

 

I'm not sure I agree with the theory that you can get reduced performance with greater than 91 octane. The owners manual does recommend 91 octane so you should always be OK running it whether it is midgrade or premium. I have heard that the original Mazda turbo engines officially required 93 octane (which is what the hp rating on a STI is with) but Mazda realized that it wasn't available. The octane rating is primarily its knock resistance so I don't see how more will cause a loss in performance, but there isn't really any reason to pay the extra given the option. I only have the option of 92 or 89octane where I live and in Colorado premium is 89 octane due to the altitude (I wonder what the dealers there say). The computer with adjust to whatever you choose to run, but it has been recommened to me that it is best to stay consistant with the octane to keep the computer from always being "out" of adjustment. A single tank of high octane won't always yield a performance increase, but over time it will allow the engine to adjust itself to run more lean.

 

Hey all, just joined on here....so far, pretty good thread going and alot of what I was wondering seems to have been discussed. I got my True Red MS3 Sport back in November, the car is a hoot and coming from a Focus ZX3....a whole lot more ethusiastic!

I've been getting about 24 mpg, but that's 90% highway so I was expecting better, more like 27-28. It has improved about 2 mpg since new, about 4500 miles ago. I've burned nothing but 87 octane as there's no way the car is putting down its full power in the winter, so why spend the extra $5 a tank.

On running this car in the winter (snow), that's easy....either you don't, or you spend the money on a set of winter wheels/tires. The RE50 tires are a pure summer tire, absolutely dangerous in the snow. I put a set of Revo's (Blizzacks) on, 205/60R16, from the TireRack and the car is as good as a 4x4 SUV. The traction/stability control with the winter tires are unstoppable. Disadvantage, though, is you don't want to run the car at high speeds with the Revo's, they flatout suck.

Where's the boost guage on this car? You guys don't mind not having one?.......I couldn't, so I put one on. What good is runnin a turbo car, and not knowing how much boost is there?!!

Anybody make a chip for this car..........it needs it bad, the factory programming is verryyyy safe. As I said, I've burned nothing but 87 octane, the cheap stuff!, and the car don't care.....at least in the winter that is. Come summer I plan on runnin super to get everybit of boost/power from this hot little motor.

 

I will never understand running fuel rated at a lower octane than what the owners manual specifies. It is ironic that you would be concerned with a boost gage and not be willing to pay the extra forthe factory specified fuel. You might actually get better mpg running 91 octane which could offset the additional price. I think the octane rating will make a difference for all types of driving, not just a full throttle. Higher compression equals higher octane and I think a turbo qualifies. Try running premium for a few tanks and see if your mpg goes up, it will take the computer a while to catch up completely.

 

Here is some number to compare:

Assuming you are getting 24 mpg (87 octane)and you fill up a full tank of 14.5 gallons at a cost of $3.00 per gallon you could travel 348 miles at a cost of $0.125 per mile.

Now assume that you could get 26 mpg using 91 octaneat an increased cost of $0.20 per gallon you could then go 377 miles on a tank at a cost of $0.123 per mile.

In a perfect world of 28 mpg using 91 octane you could go 406 miles on a tank at a costof $0.114 per gallon.

Think about the possibilities...less stops for gas, higher quality fuel at a lower cost.

 

By the way CT MS3, welcome!

I didn't mean to "flame" you after your first post. What a butt-head that makes me

I do think that the premium fuel will pay for itself and you should give it a try. I am getting 22-24 mpg so far and I have not even come close to a full tank of highway cruising and Ihave under 2,500 miles on the car so I am hopeful that I can see the same mpg increase that you did over time.

 

Hey Nor_3_Cal,
Congrats and welcome to the forums!
I like the ms3 in silver, though I wish they were offered in a few other colors than they are. Silver would probably be my choice too.

 

I'll no doubt start runnin the 91 or better octane once the weather turns warmer, but in the beginning when the first 500 miles was put on the car and using super, the mileage was no better. The benefit of higher octane is the resistance to knock, mileage improvement is not what octane does. I've seen where higher octane actually reduces mileage, so who knows. In my neck of the woods, runnin the cheap stuff saves almost $4 per tank, so why not?
Besides, all my other turbo cars get less than ideal mileage too, I just think it's a turbo engine's nature to swill fuel. I do know, there is no way this MS3 is getting 30 mpg as the sticker says it might.

And so far the car had some solenoid warrantee replacement, I don't think it was the purge valve solenoid thingy that was posted alot about. I still think all is not right though, as the cooling fan goes on and off (2 seconds on) when the car idles. I have noticed the tail pipe is less sooty, but still black no less as the car has almost 5k miles on it now.

 

My mileage has gotten better over time,I have gotten 25+ on the last three tanks and 26+ on the one before that. There have been some highway trips, but they all involved some mountains, four passengers at times and a lead foot. One of the tanks had about a hundred miles with four people where we were playing with the car up to 120 mph a few times. I have no doubt that in good highway conditions the rated 28 would be easy. I say spend the extra $12 and give premium a shot for three tanks and see if your mileage goes up by 2 mpg to pay for itself. Higher octane often is a waste in the computer controlled cars that don't require it, but I'm not sure I have heard of a car rated for premium doing better on lower grade fuel.