Hey all,
If you read any of my past posts you'd have seen that I've been
pretty dissapointed with my gas mileage. My car has 2300 miles on it
and I was consistently getting 12-13 mpg.
My driving consisted of about 65% highway/35% city in cold
temperatures. 30 degrees and lower. My shifting habit included the
majority of my gear changes around 4000 RPM on average and I rarely
ever ran the car hard.

After reading a post by Maurice (canzoomer) that stated that the
second intake port opens up at 3750 RPM I decided to try an
experiment.

I drove an entire tank of gas shifting under 3000 RPM (around 2700).
The results where phenomenal in proportion to the MPG that I was used
to getting. This last tank gave me a whopping 18.7 MPG with outside
temps in the 30's and 65% highway/35% city driving.
I was shocked to see such a difference by shifting at a slightly
lower RPM.
The opening of the second intake must dump quite a bit of gas in the
motor.

I'm glad to see that it is possible to improve the fuel economy but
at the same time...IT WAS THE MOST BORING 243 MILES I'VE EVER
DRIVEN!!!!!!!!! People in econoboxes were passing me by like I was
standing still and giving me dirty looks. (perhaps my imagination).

Although I found a way to increase gas economy I feel like I'd rather
be in an automatic if I have to drive to slow. Not to mention that it
was nerve racking trying to keep the revs so low as to not disrupt my
experiment.

I'm still discouraged that it has to be this way but at least I know
it can be done.

BTW- I read that gas prices might hit $3.00 a gallon by summer.
Yeah!!!!!!

Gary

if it hits $3 this summer my Miata will see a lot more duty! I've been averaging 21MPG; hit 4-5K regularly, except on the first shifts of the day - I hit the highway .1 mile from my house - so I take it easy the first 5 miles. That includes some rather aggressive driving and I try to hit 9K at least once/day.

21 MPG?
In cold Maryland?
87 octane hasn't been a problem?
The $3.00 article was on netscape but I can't find it now.

GT

Very similar to an experiment I tried back in October....

'Zoomer was heavy into the details of the fuel maps, and mentioned that the curve got quite LEAN above 5000 revs.....
O.K.....I can handle that - so I used a tankful, NEVER letting the revs drop BELOW 5k!

MAN, that was fun! and actually harder than it sounds! however gas mileage sucked even worse.

I thought it might take plastic surgery to get the silly grin off my face!

S

Why the huge dump at 3750 then??????????

I posted a while back of a 30.22 MPG I got on my way back from Reno. I did this over a 100 mile stretch. I got flamed and called BS. I did this under 3000 RPM, about 57 MPH on cruise control.

If I drive 3500 RPM on the same trip back I get 25-26 MPG.

I just did my own mini mileage experiment.

My highest mpg was 19.2mpg on my second tank during careful break-in regimen. No shift over 3500, no driving over 65, varying rpms constantly.

Subsequently, all tanks have been in the 17's and 18's. My weekly schedule is always the same. M-F is light stop and go, short trips under 4-5 miles. My weekend has two highway runs of 65 miles at 75+mph.

All tanks are 93 octane, various premium brands - mostly BP/Amoco.

This past weekend, I had to fill up just before getting on the highway. There weren't more than 3-4 traffic lights before getting on the highway then a straight run for 65 miles. I do mean straight run - this is FL - no hills, no headwind, temp about 58 degrees. Kept the cruise between 73 and 75 (just under 4k rpms). Got off the highway and sure enough, 17.64mpg.

The prior tank was 17.92 and that included plenty of short hop stop and go.

My conclusion, in my car's current state of tune/ECU mapping, it doesn't matter how you drive it, you can't baby it to get better mileage.

I have noticed that there is a misfire at idle lately (cold or warm) and I will have the dealer check it soon, but I'd be surprised if that alone could be responsible for the mileage.

I just got 18.3 MPG in a 170 mile fill up, that was gentle driving (getting passed by econboxes as well) and I only broke 3500 RPM a few times. About 100 of those were urban miles, 40 were expressway, and the last 30 split between city and rural. The dominant drive has been 7 miles to and from work, in cold weather.

I think the city driving, with time spent at stop lights, really degrades the MPG. We also have an Odyssey, and I have started taking that for stop and go city driving. I have also started considering taking longer routes that have less stop and go.

Does anyone know what the consequences or symptoms are driving a rotary in low RPMs? I purposely get it on the expressway once a week to get it some revs.

<Mar 18, 2004>
My last four tanks were 19.3 - 19.9 MPG for city+highway mix, including some high revs on every tank. I am getting good results from Regular and may have a different acceleration noise after two consecutive tanks of Reguar.

I am consistently getting 19.2(city)-20.4(highway) from my 8. It is Louisiana so I know that makes a difference for you Northern guys, but I drive it hard one day and easy the next with similar results. I have 6133.6 on my odometer and it has produced the same mileage straight out of the showroom. Maybe you should take a trip down here and see what the car does? Besides, you never know what you will find when you wake up here,whether it be rain, sun, hot, or cold. Always an adventure.

At 3750 rpm the secondary fuel injector comes on line

more rpms + more fuel (and air) is going to hit mpg.

I've averaged 19.6 mpg in my first two tanks. Mixed driving, cool-to-cold temperatures (MD), and shifts at around 3500-4000 rpm.

Beachdog, I've noticed a slight misfire at idle as well (cold or warm) -- it's nothing dramatic, and it stops as soon as I touch the gas pedal.

If you've seen my threads, you know about my 10-12 mpg/city complaints. I wonder how difficult it would be to reprogram (or make mechanical adjustments?) that would extend the the 2nd port opening from 3750 to say...4,500 or something? That way, you could cruise in 6th and not get run over!

Originally posted by GTF-RX-8
Hey all,

I drove an entire tank of gas shifting under 3000 RPM (around 2700).
The results where phenomenal in proportion to the MPG that I was used
to getting. This last tank gave me a whopping 18.7 MPG


IT WAS THE MOST BORING 243 MILES I'VE EVER
DRIVEN!!!!!!!!! People in econoboxes were passing me by like I was
standing still and giving me dirty looks. (perhaps my imagination).

Although I found a way to increase gas economy I feel like I'd rather be in an automatic if I have to drive to slow. Not to mention that it was nerve racking trying to keep the revs so low as to not disrupt my experiment.

Gary


LOL Gary

I thought I would try a similar experiment- I only made it about 2 miles down the road before I accidently started reving it up again :D I'm very impressed with your show of self restraint!

Will,
That would definitely be a good idea. I think Canzoomer's ECU mod is supposed to improve the air fuel map somewhat better than stock.

I know I'm going to get flamed for saying this but a shift light wouldn't be such a bad idea either. perhaps one that you can turn on or off.

:)
Gary

Silvercloud,
It wasn't easy!!!!!!!!!!

HEHE!

Gary

I have consistently averaged 19 mph since I got the car (2000 miles). It drops to under 17 when raced a lot, well over 20 on the highway under 70 mph. I usually shift at 4000-5000 in first and second, and accelerate moderately. I am very conscious of minimizing braking in traffic. I watch ahead and coast a lot. My daughter took it for a day and got under 15. She tends to scoot from traffic light to traffic light and brakes heavily.

so to say I should really keep my car above 3200 rpm when cruising on highway?... another excuse to cops. :p

It's been a while since I posted but I too did this "experiement" in September 03 and found the same results.

Rodster-
were you getting low mpg in sunny florida?

Gary

IT WAS THE MOST BORING 243 MILES I'VE EVER
DRIVEN!!!!!!!!! People in econoboxes were passing me by like I was
standing still and giving me dirty looks.


-At this point I acctually laughed so hard I farted. You da man for following through with the experiment.

LOL! Thanks! Could you bottle that gas and send it to me?

I tried the experiment once. Lasted until just after I turned the key. If I wanted mileage, I wouldn't have bought this car. God killed the dinos so we could drive fast, not so we could worry about MPG.

GuysI know you say this isthe best way to get highest MPG but Iam almost positive Ive donethis before and all it reallydid was frustrated the hell out ofme. I do 100% city driving so maybe that is why I got nothing out of drivingthis car like an old lady.

Had a chat with a friend today, and he told me his interesting way of getting more miles out from his drive.

Well, he never pump a full tank of petrol, imagine, 58-60liters when full, that's alot of extra weight to run around with! So for those who can excess to petrol station easily might wanna try this. Just go with half tank, don't fill up anything more than you need. Basically is a weight theory.

cheers

Keeping the tank mostly empty all the time is not good for the tank in the long run if it's metal. Do we have plastic tanks? I never looked...

Those of you who have the stamina to shift these cars under 3K for 200 miles or more amaze me. This car is no fun under 4K! Might as well be a diesel under 3K.

I'm currently trying this experiment. Not that I'm getting horrible mpg (about 19.5 over the last 10 tanks, 50/50 city/highway), but I want to see if it'll go any higher. Normally I drive fairly aggressive, so I think i'm blessed with the mpg I do get. I still take it to redline once a trip to clear out any bad stuff that may build up. I noticed that after driving around town, shifting 3.5-4k, and taking the revs up I get some significant backfiring on the 1-2 and 2-3 shifts. Sounds pretty cool :D . It usually happens after driving a while, so I guess the exhaust gets hot.

I went ahead and tried the "keep it under 3750" rpm driving style for 177.7 miles (thats a long as I could stand it).

As some of you may have read, my average MPG is 11-12.5 mpg. Using this low-rpm driving style, my results: 177.7miles/11.77 gallons to fill, or ~15 MPG, an improvement of 2.5-4 MPG, or about (give or take) 30%.

Not a bad improvement, still 15mpg isn't anything to really brag about, but its certainly better than what I got in the past-- mind you this is 100% city driving.

However, it just isn't worth it... I mean, I have to shift 1->3->5 otherwise I'm shifting through the gears silyl fast... and of course, its REALLY boring to drive this way.

In conclusion, I'm just going to drive it with the higher rpms and suffer the gas milage.. but I do think in the highway I'd probably see 16-18mpg (I think keeping the rpms under the 3750/keeping the 2nd port from opening) helps a lot on milage.

Ohh..FWIW, I should state that I drove this style probably 85% of the time-- there were a few times I had to use the power to get outta my own way, etc..

Originally posted by therm8
Not that I'm getting horrible mpg (about 19.5 over the last 10 tanks, 50/50 city/highway),

Man, you're getting 19.5 with an auto? :eek:

Shit, I wish I was getting 17 with mine; I'm probably around 14-15.

19.5 is amazing. Whatever you're doing, I wouldn't change it. :cool:

first 5k miles avg was 16-17mpg have notice a pretty dramatic improvement after 7Kmiles hwy mileage now avg 20-22. 90% of my driving on the hwy ( rarely seeing posted limit) closing in on the 9k mile mark now

Recent Carolina-Colorado round trip, ~3,500 miles, ending with 7,369 on odometer:

Average fuel mileage: 20.32 MPG
Low: 17.6 (80 MPH, Stinkin' McInterstate)
High: 22.6 (Colorado-Kansas, 1 mile elevation drop, snow, ~2-2,500 RPM in 6th). Because of weather & schedule, this was a boring slog, with great effort put toward maximizing fuel stinginess.

I do this trip once or twice a year (passes for a commute in my world) -- sometimes in my old Miata, more often in my silly old Jeep. The Miata typically averages about 36 MPG, gets within a whisker of 40 dropping out of Colorado, and always drops into the 22s when the whole tank is expended between 100 & 125 MPH. Miata trips are generally about 2,000 miles and a week longer, with emphasis on interesting back roads. Jeep trips are similar, without the wailing on the twisties, but with some 4W-LO action. The Jeep (a 5,000 lb carbureted V8/slushbox behemoth) averages about 10.5 MPG (high of 13.1, low of 1.8 -- yes, that last decimal is in the right place).

}}}}

Call me crazy, or an 8 abuser, but I will tend to shift very high. I allow the car to warm up for a time, but once it is hot, it is not uncommon for me to leave it at 5ooo rpms for about 1o or 2o seconds before I shift. Several times per run I head up to 7ooo and then at least once I head up to 9ooo.

My mileage has been between 14.2 worst case, and 21.6 best case. I tried the gas mileage tests but with a two stage learning fuel map, I found it to be tedious and next to useless.

enjoy the ride

thats what it's there for.

Also, rotaries like to be higher on the tach than reciprocating engines. Let it rise, and then laugh at the people in the cars next to you, as they laugh at the money your 8 is drinking as fuel. there is a trade off for everything.

And here I thought I was the only one getting rotten mileage! However, I don't think I possess the self control necessary to keep it under 5K, let alone the 3500 (I think it was) discussed.

Well my experiment is over. Averaged 19.5 mpg with my "Normal" driving, and just a hair over 20 mpg using this thread's technique. And that is kind of what I was hoping for, just means I can drive my car how I like to and not wonder about mpg.

I passed 5K miles last week, and will be making a 650 mile highway run in about a week. I'll post mpg results after that. haven't made any long trips yet, and I'm interested to see what kind of range I can get.

On a side note, I have noticed in the past couple of days that the car seems...only word I can think of is...peppier. Pulls harder, especially in second gear. I don't know if it's because the weather warmed up (seems backwards to me) or what, but that's the only thing that's changed. Hmm, maybe someone slapped a Type R sticker on my car (that might cause my apparent power increase :D ), i'd better go check.

Hey therm8,
Thanks for the update.

After my original experiment I ran my last tank "normal" also and got 17 mpg.
The outside temperature has been in the high 40's as opposed to low 30's and that seemed to make a huge difference.

It's amazing how in 30 degree weather I was getting 12-13 and yet with a 10 gegree rise I got 17.

Weird!!!!!!!

Gary

It seems like there is a bit of variation in gas mileage. I drive 40 miles one way to work all highway and get 20 mpg at 75 mph ~3700-4000 RPM. Does anyone have any experience with the effect of different driving habits during the engines breakin period? I noticed there was one post about the gas mileage going up after someone passed 7K miles on the Odo. Could there be a relation ship with how young the engine is for the first 5-10K miles? Just to put everyone in a bad mood, the first specs on the C6 vette just came out and MT says they've gotten 30 MPG with a 6.0 V8.

i have 1700 miles on my 8 and it is getting has been getting about 10miles more per tank full .i always get gas when the gas light comes on and it always takes 13.5gal.maybe the more it breaks in the better the mileage will get .if not i'm still enjoying it

How anyone is getting 20 mpg or close is beyond me. I have had the car for 6K miles now and I get between 11 and 13 mpg. Granted it is all city driving but it still seems very low. I live in S. Fla and had the car through the winter with no change in gas mileage.
I am thinking of having the ECU flashed to "L" version per other threads. Don't know if that will help but I know I don't have the "L" flash because I did the test posted in other threads and the oil needle did not move. Hopefully the "L" flash will help improve my gas mileage because this is ridiculous. I would be happy to get 15 mpg.
Once I get the ECU flashed I will update this thread with new mpg.

Originally posted by SMigneco
How anyone is getting 20 mpg or close is beyond me.....

I've been getting close to 20 mpg on 87 octane for all of my 5.5k miles. I got close to 21 once on a mostly highway trip, but did not fill up till I had done a bit of local driving.

I've got to wonder if I'd get my usual 19-20 mpg if I drove one of these low mpg cars for a week. Or for that matter, I wonder if people getting low mpg would get 19-20 mpg if they drove my car for a week :D .

I don't drive my car like I stole it, do you?

rx8cited

I use 93 octane and redline at least once per drive but not every gear. I usually shift between 3500 & 4500 RPM's when driving normally. I was reading in one of the threads on this forum (not sure if it was this same thread) that someone was getting around 10mpg and found out that it was a bad O2 sensor. Maybe I have the same problem. I will have to bring it to Mazda and complain about the horrible gas mileage to find out for sure.
Like I said, I already know I don't have the latest ECU flash and many people (though not all) have said they are getting improved gas mileage after having the ECU flashed to the latest version.

Originally posted by SMigneco
How anyone is getting 20 mpg or close is beyond me.

I honestly believe it's all about the highway driving. From the very first fill up, I've always managed at least 19 MPG on my 8. I'd say I do 80-90% highway driving, although a fair bit of that is in stop and go traffic. Now that I'm past 7000 miles and the weather is getting warmer, I've been getting 20+ MPG over the last few fill ups. All this is with crappy winterized gas. Once the warm weather comes and we get the good gas back, I'm hoping to break 22 MPG on a regular basis.

I tried this, it had little to no effect on my MPG, that week and a half was painful.

Shifted between 3000-3250 the entire tank 15.9 MPG.

The only time it gets significantly better is if I take a road trip and am able to cruise for long distances between 60-80 MPH in 6th.

Originally posted by GTF-RX-8
Although I found a way to increase gas economy I feel like I'd rather be in an automatic if I have to drive to slow. Not to mention that it was nerve racking trying to keep the revs so low as to not disrupt my experiment.

Is that a slur on the automatic I hear? GrRRRrrrrrRRrrr...

Oh well, don't get me started on this subject again...

Wait a sec! I already am started...drat!

How anyone is getting 20 mpg or close is beyond me.

P.S. I am getting 20-21 MPG on my daily trips to work...driving normally (98% Highway).

Katchoo,
Not a slur.
I was referring to "ANY" automatic when I wrote that.
Not just an 8.
Tedious manual shifting is rather tiresome when you can't enjoy it.
:)

I am now at 18,000+ miles and my 8 has been getting 20 mpg consistantly since about 7,000 miles. And when I say consistantly, I mean consistantly!! I only check occasionally now because it is ALWAYS 20 mpg. The decimal changes, but the 20 never does no matter how I drive. I commute about 55 miles of highway to work and about 85 percent of my driving is highway. I had the 'L' flash done last Monday and have went through 3 tanks since and milage has not changed one iota. The car does feel a little smoother and seems to have a little more power on the low end since the ECU flash. It was flashed because i had a CEL indicating "out of parameter".

For what it's worth, my 8 just turned 10,000 miles. I've consistely had around 18mpg the way I drive. Worse if I follow the shift points in the owners manual.

However, I have adopted a new technique that is bringing me 21mpg and my first 300 miles on one tank of gas. I drive normally but exclude 6th gear entirely unless I'm above 72mph.

I don't know if this will buy anyone else any better results, but on my car it's working. I next want to try cruising at slightly higher RPMs and see if that improves the numbers or makes them worse.

Seems to be at cruising speed ~65-70mph over long distances I'm doing better without 6th gear.

Martin

300 miles on one tank!! I have yet to see 200 miles on one tank! I fill up at a little under 1/4 tank and I am usually between 180 & 190. I have tried many different driving styles but the mpg has not changed. I have an appt. on Tuesday 3/23 to get the recall's taken care of and I am going to have them check the O2 sensor.
There has to be something wrong. I live in a warm weather climate so the absolute coldest my car has seen has been in the 50's. No change in gas mileage no matter what the outside temp.
When I setup the appt. for the recall work I asked my Service guy about the "L" reflash and he did not know what I was talking about. I then told him I have a copy of the Mazda Service Bulletin issued regarding the "L" reflash with the part # of the reflash. He said that as long as I showed him a copy of the bulletin with the part # he would have no problem doing the reflash for me.
I have had nothing but great experiences with Lou Bachrodt Mazda so hopefully that will continue. They gave me a loaner 8 when I had the leather put in my 8 and they told me when I get the recall work done they will give me another 8 as a loaner. I will keep everyone posted on how everything goes after Tuesday regarding the mpg.

I can't keep it under 3700 rpm coming out of my driveway!! I have been getting a little over 18 mpg the last 3 or 4 tanks. when I first got the car I was getting 14 mpg; have 2300 miles on it now.