I've had my 3 for about a month now, I have found out that my car does not like 87 octane gas, must use 89 or higher. With the 87 my gas mileage is horrible. Also if someone can find out why Mazda gave the Designation "R" to some models. When I purchased it the dealer said they could give me a better deal on any Mazda that had the "R" designation. I'm wondering if this has something to do with the gas preference.

 

So which of three engines do you have in your car; the 2.0, 2.0 SkyActiv-G, or the 2.5?

 

I have the 2.5

 

It is the 2.5

 

To say that I find it highly unlikely that your 2.5 liter engine would deliver lower fuel economy on Regular gasoline as opposed to Mid-Grade or Premium is an extreme understatement. As a general rule, engines designed for Regular (the 2.5 is one such engine) will deliver better fuel economy when run on Regular.

 

This is not my first Mazda, I've had four since 2003, and have never encountered this kind of fuel mileage from any of my past cars. I took a trip to see what kind of mileage I would get. When I left I had 89 octane in the tank, when I arrived at my destination I filled up and check my MPG, it was 30 MPG. When I filled up I used 87 octane from BP, on the return trip the MPG was 23. So whats up with that, I have my Mazda Dealer looking into this. Hopefully this can be explained.

 

There are any number of things which might explain what you experienced; the thing is, one tank does not a test make. Pumps click off at different points of tank "fullness", fuel quality varies, weather conditions change, traffic conditions are rarely the same...

If you run five consecutive tanks with one grade of fuel, and average the fuel consumed against the miles driven, and then repeat the test with a different grade of fuel, and assuming the driving environment is similar, then you will at least have some compelling anecdotal evidence to point to. One tank up with one grade of fuel and then one tank back proves nothing.

Long story short, there is absolutely nothing in the properties of an 89 AKI fuel versus an 87 AKI fuel which would embue the former with the ability to improve your mileage some 30 percent above what you reported from the latter. Can't happen; it is a physical impossibility.

 

Shippo, please write a book about mazda 2.5's. I would love to read it.

 

I am going to buy this. I am an MPG nerd and always try different octane levels in vehicles to see what they prefer. If the engine has a lower octane than what it can utilize, the knock sensor will simply drag the timing back and seat of the pants isn't a good judge. One has to run many tankfuls, filled from the SAME pump, and drive the SAME route, and do this for a while to establish a good pattern. I have done this.

I have a 2002 Ford Ranger with a 2.3L version of the Mazda 4cyl. I experimented and found that it gained about 2MPG with 89 octane. I bought the truck new and it has over 120K miles on it and I will guarantee you, hard numbers, no BS, 89 Octane, with factory plugs, wires, and air filter, delivers at LEAST 2MPG better than 87 in the central Ohio area.

Since then we have had a 2000 Honda CR-V (my current driver) and a 2003 Honda CR-V, and none of them cared what octane I used, the MPG seemed to stay the same.

So when we traded the 2003 V in on a 2012 Mazda5, I figured I'd give 89 a try. Guess what? While I don't have enough tankfuls to establish a pattern, it does seem that I am gaining about 2-3MPG with the 89. Whether 93 would make any difference or not I don't know.

Now you say that this shouldn't make any difference and you may be right. But get this. I don't remember where I read it but a TV station gathered fuel samples from something like 20 fuel stations and found that over half of them did not meet the minimum octane as listed on the pump. Furthermore, I know of two incidents that the ethanol blend (mandatory 10% in the USA) was so jacked up that the cars had to have their tanks drained and fue systems purged; one was my fathers 2007 CR-V.

So in closing, it's entirely possible that the 87 octane is actually a point or two lower and is causing knocking, which isn't noticed because the sensor drags the timing back. Now 89, by nature is a mix of 87 and 93, mixed at the pump. Logic would indicate that while the 89 may not be 89, it most certainly is 87 and thus meets the requirement. Personally, I think that from my experience with my Ford Ranger (2.3 Mazda) and my 2012 Mazda5 (2.5) that the engine will run quite well on 87 but does tend to utilize the additional benefits of 89. That's my experience.

One more thing. I noticed in the Mazda5 the slightest bit of hesitation when leaving a stop sign. Not a stumble, but more like the electronic throttle was taking a split second to sort things out before spooling the engine up. While again, I am not positive about my observation, it felt like to me the engine did NOT do this on 89.

WHEW!!!...BOTTOM LINE: One must compare for themselves and make their own choice.

 

Thanks TroyOHchatter for that info, my 3 now has 12,000 miles on it and it has settled in on the manufacture's stated MPG. I'm happy with the local mpg but still not the highway mileage, don't think that a person must drive 55 to 60 to get at least 30 mpg's. My previous Mazda was the 6 with a 2.3 engine, i drove that car faster than I do the new one and received better highway mileage. I averaged 29 to 32 going 70 to 80 mph, so go figure why this 3 is unable to do the same.
As you stated about your 5 my 3 also has the same issue, I do call it a hesitation because once I press the pedal there is a delay in response to that action. I also noted that same when I pull out into traffic and then see that I need to pick it up bit that the response again is delayed. I never experienced this with my 2006 Mazda 6, response was always mediate.
Another quirk this car has is the brakes; I deem them only adequate. They are too mushy and require a lot pedal travel before they start to engage. I've had the dealer look into this to be told that the brakes are good. I guess I must have had an exceptional Mazda 6 because I have nothing bad to say about it. My 3 should easily out do the 6 I had, but at this time I don't think that will happen!!!