MazdaRich

Altitude and speed seem to make the biggest difference in my highway mileage. I can get about 25mpg at 7000 feet and above, but keep in mind most of the time I'm only driving about 50-60mph due to the how tight the roads are up there.

Running 80mph through Kansas nets exactly the same mpg as my mixed driving--roughly 21. Normally I drive about 60-70% highway at 5200 feet. I think if I made the same drive at about 60mph, I could get the claimed 24 highway. This leads me to believe that wind resistance is the biggest factor in determining mileage. Engine RPM doesn't even make that big of a difference. A taller rear-end or sixth gear would seem to make a lot of sense on this car, and I don't really understand why it's so short. It probably is mainly to prolong engine life, in exchange for a little lower mileage at 80mph.

Winfree

Don't know how I got it - tank came with car - will double check holding capacity - that would really make gas usage better since that would only be 3 gallons more than the 323 and yet delivering the same distance - she is a sweet one!

zoom44

fuel tank capacity is 15.9 and NOT 18

DrDiaboloco

Mazda's website says 15.9 gallons.

Winfree

I'm a willing victem - if its only 15 that means I am getting really great MPG convers it means my local stations meters may not be accurate and they are posting more gallons then are being delivered -

MazdaRich

if you are putting more than 14 gallons in the car when you fill up, you are a madman who ignores the fuel light for a good 30-40 miles

DrDiaboloco

Well... Since the light coming on doesn't mean "you're going to run out of fuel in five minutes", this is hardly the work of a "madman".

Winfree

I understand that most of you are paying less than $3.69-3.21 per gallon of hi test (local Calif. evil prices)- what are some of your prices and how much do you usually spend to fill/top off your tank?

Paul_in_DC

Paid $3.14 today for Shell 93

RazzyBRX-8

The last I paid for my gas was $2.83 a gallon. Cost me 39 dollars for 13 gallons of gas. Give or take

Raptor2k

You're contradicting yourself a little right there...of course you're going to get better mileage going 50-60 mph (less work done by the engine, less air resistance) than going 80 mph (~4000 RPMs). How hard you work the engine makes a big difference in gas mileage, I think that's a universally accepted fact.

turbine

Your tank could be 1000 gallons. The point is moote. You divide the gallons you put in your tank by the miles on your odometer. Given you reset it on every fuel. There is your Miles/Gallon.

turbine

75 MPH = 23.8
80 MPH = 24.3
85 MPH = 25 or better

This was what I observed from a 1700 mile trip in June. High temps going through mountain passes too. 4k to 4.5k RPM seems to be the best for continous burns. I believe we get an advantage over a piston driven auto's. The rotars are not turning cranks that have to turn a drive shaft. They tumble with the shaft. The energy stored up in the mass offsets the fuel needed for that RPM. Helicopters use this concept for emergency landings. It's called auto-rotation. In the event of an engine failure, we clutch the engine from the spinning rotars and set blades for no chop. As the chopper falls to the earth the blades are spinning by their own weight. At 100 foot you pitch the blades to full chop. This counters the fall to a light crash at worst. You really get to thinking on a long trip. My girlfriend slept both ways. Memphis to DC, DC to Memphis. On the way back, we left DC at 12:30 P.M. We stopped for lunch for about an hour or so. We were in the driveway at 1:30 A.M. We did cross a time zone and stops for fuel. Not bad.

Just a theory, but my only thoughts to why the dam thing gets better gas mileage at higher cruise speeds. I use cruise control too. I keep a fixed speed as much as possible. I have put 54,000 miles on it. Drives better than it did with 2 miles on it. I get about 18 in the city. Make sure your shifts should be made so that the next gear see's at least 3.2K RPM.

Raptor75

Describe what your city driving is like. Stop and go? Lots of ideas? I can't believe people can get this in the city. My city mileage is 12mpg.

DrDiaboloco

Like any other car, there's a single speed in top gear that offers the highest MPG. No way to know what it is in the '8 without consulting a scientific comparison, but I doubt that higher RPM is the answer... And helicopters have nothing to do with it, either. Don't think that I don't understand what you're getting at, I'm a professional pilot with a degree in Aeronautical Engineering and I'm familiar with the aerodynamics involved in helicopter flight (even though I'm not a helicopter pilot).

I've achieved your alleged mileage at 85mph at 72-75mph, and I highly doubt that it'd improve if I ratcheted up the speed by 10+mph. I'm not sure how you can allege to have these scientific numbers at three different speed points, the lowest of which is the minimum needed to complete the trip with the quoted hour-long lunch break... Your average speed over the trip (850mi in 13hrs, not including your break) is effectively the same as mine on a recent highway trip (700mi in 10.7hrs, INCLUDING stops and traffic tie-ups in metro areas and construction sites)... A trip during which I never exceeded 75mph... And in which you claim to have mileage numbers for a speed 10mph higher than that which I was travelling.

Do you see where my skepticism comes from? Drop the hour-or-so lunch break and include fuel stops and somehow I'm still achieving a slightly higher average speed while only going 72-75mph MAX on the road!? Are you REALLY doing 80 or 85mph for a whole tank and coming up with those numbers, or are you just making suppositions?

And these numbers from my end are on a nearly-new car that has theoretically lower MPG than a well run-in car. I'm not trying to be a dick, but something doesn't add up here.

Winfree

How much does the presence of a passenger effect milage? Luggage? Also does anyone know how many rotations of the wheel we get per rotations of the rotar?

TwincH

My latest mpg was 14.6. I live 1.7 miles from work so basically, I fire up the motor, let it warm up, drive 5 min, then I'm at work. There was a little bit of highway driving on this tank so if it's all city driving, I'll probably get worse mpg.

2005 AT with 1000 miles on the clock.

mcsetech

Listen kid....I don't bullshit. I have owned several cars and I know what I'm talking about. I don't appreciate your arrogant attitude....

I bought the car because it appealed to me. After being an owner for seven months now I've been able to evaluate the car to its full capacity. OF all that time the car has been in for service six times I shift when I need to and never race the engine. I've have driven the car on the highway for a full trip many times. People like me that have money do go on long trips punk...

mcsetech

I think there is something wrong with my car. Mazda doesn't want to address it. I think the MPG can be atributed to the car having some sort of rotational drag. I found that my car actually slows down on a decline. Brakes hard to right at times. It's on its second set of tires. I've had the brakes checked by brake specialists and they have found thing wrong with the brakes. Mazda blamed the wide tires. I have wide z rated tires on my Mustang and don't have these problems. I'm really not sure what the problem is. I think the rear end mybe out of alignment. I feel Mazda should pay for this as it would seem it came like this from the factory. I've had several cars and have never run into having an alignment during the break in period. this car has had poor MPG right from the time it was bought. I'm disappointed in how Mazda doesn't stand behind their poor quality.

Paul_in_DC

Why would someone waste time whining on this forum instead of getting their car fixed? If anyone really got 13 mpg for highway driving there'd a severe problem with the car. Seriously, the last thing someone would realistically think of doing is complaining on a forum. That kind of BS (plus two set of tires and 13 posts) makes you sound like a troll.

zoom44

i am 38 years old. im not a punk and while i may be arrogant its because im right. you can not get that kind of mileage on the highway. period end of story. since you aren't bullshitting then you must be an idiot. i dont care if your rich or poor or what ever kind of people you are. you dont know what you are talking about. your car literally can not pump that amount of fuel on the highway at anything appproaching normal speeds. on a track- sure. if you drive on the highway like its a race track then you are complaining about yourself. and an idiot.

Paul_in_DC

Sometimes I suspect that people who are reporting bad mileage may just be goofing up on the calculation. I've gotten 10 mpg before, but only at the track.

- Fill up your tank.
- Reset your odometer to zero.
- Drive.
- Fill up your tank again. Note the number of gallons it took to refill.
- Note the number of miles on the odometer.
- Divide the number of miles by the number of gallons.
- Check your work.

Repeat the same process over several tanks to get an average.

Raptor75

Seeing that I have a degree in Mathematics/Computer science I never really considered calculating gas that big of a deal.

It is easy to right off someones poor mileage until it happens to you. The guy above could very well have a issue with mileage and I am sure that as soon as Mazda hears "gas mileage issue" they turned their back on him. This is the big problem with Mazda, the RX gets poor mileage normally. When an RX has a problem which effects gas mileage Mazda instinctively assumes it is just another person complaining about normally poor mileage. The end result is those who truly have problems are never serviced or corrected.

Here is my record mileage to date.

SecrtSqurl

I had a problem after I lowered my car andchanged the rims. They were supposed to check the caster, camber and toe-in. After I noticed my right rear wearing more than the other tires, I took it in and had all three measured again. Sure enought the right rear had more negative camber. I had them remove as much negative camber from both rears (ended up at -1.2). It hasnt had a problem since.

I am not sure if it was sloppy work that caused the proble, or something that did while driving the car hard. Either way, it was cheap to inspect and to repair. I got everything done at Les Schwab.

DrDiaboloco

As promised earlier... A screenshot of my mileage spreadsheet, with all the detail I think you need to see what sort of mileage my car is getting.

I have broken down some things that may not be immediately apparent, so here are the translations:

In the FUEL column: PREM=91, Mid/Plus=89, Reg=87

In the NOTES column:
Interstate: Means a steady 72-75mph (in 65-70mph zones) for long stretches, broken only by traffic, passing, or other obstruction.
Highway: Means steady 62mph (in 55mph zones), broken up by stop signs, railroad crossings, passing through towns with much lower speed limits, etc.
Local: In-town driving, all at posted 45mph or below. Frequent stop-and-go, minimal redlining... At most one "beep" per trip, predominantly below 5-6000rpm.
Rain: Self-explanatory. Moderate-heavy rain on this particular tank (these are only shown on stretches that are otherwise categorized as "Interstate" as of this point).
A/C: Use of air conditioning is either Light (under 15mins/hr) or Heavy (45mins or more per hour). Even though it is only mentioned on "Interstate" tanks, my last three tanks were all in the "Heavy A/C" category.
Anything Else: Information to remind myself what the trips and conditions were like. Mostly city/state codings.



There is one tank, the most recent one, that is not included in this spreadsheet because it's sitting in the car and I'm too lazy to go get it. It would have little effect on the average as it's roughly 19mpg.