Dedicated to improving gas millage, by any means!

[RABID_MP5]

Since I have 205/50 R16's, wouldn't my millage be slightly higher then I'm actually calculating? btw, I am calculating by resetting my pedometer after an exact fill up (when the pump clicks), then dividing that number by the gallons for the next fill up, and so on...

yep, using http://www.miata.net/garage/tirecalc.html you'll see you're 1.7% bigger than stock 195/50s for say a P5. So you're really doing that much better then you calculate. But in reality you should now be using slightly less gas than stock, maybe 1% or so. Of course the extra width may be eating this up
One other note on all this, if 10/32" tread gets worn down to 2/32" your diameter decreases - by 16/32 (the radius x 2) , or 1/2 inch (!) This is a 2% change. So yeah, your observed mileage does increase the farther you go...

 

[RABID_MP5]

all in the timing

Hey is '02 2.0 ignition timing user adjustable? I realize this is just the start point of the curve and that ECU data and knock sensor, any turbo etc. then come into play. But certainly traditionally you could advance timing till knocking was just imminent and back off a tad and usually max out the mileage. On my 96 626 you jumpered a wire on the test connector and maybe pulled the vacuum advance at hot idle and set it. But with no distributor, how is this done? Can't find a how-to....

 

[TXMazdaSpeeder]

timing is ecu controlled, therefore you'd have to have some sort of engine management such as a piggyback or standalone ecu. The mp3 ecu would advance the timing but lacks the necc. programming for boost and requires 91+ octane.

 

[kura808]

-hmm drive wit the windows up while on the highway. i'm thinking +1 or 2 mpg
-get a less restrictive exhaust(get a racing beat xD or mazdaspeed exhaust from ur dealer) i know when i got my mazdaspeed exhaust, i swore i got about +1 or 2 mpg more per gallon.
-uhh did u do ur check ups? like air filter, oil, etc. thats what was robbing my mpg b4.
-ur tires are bigger than stock i'm thinking cause on my p5 it was 195/50/16 but when to 205/50/16. ur gonna lose a few mpg wit those wider tires.
-dont use ur brakes too much. coast when necessary like down hills and stuffs.every time u use ur brakes, u gotta use more gas to get going again. let ur car use its inertia xD
-yea like every1 else said, it depends on ur driving habits. hopefully ur not WOT all the time lol xP but if u get a nice exhaust, u probably will lol

 

[kura808]

o yea get rid of unnecessary things(weight reduction) in ur car like extra seats and crap u dont need. more weight= more mass to get moving which uses more gas

 

[Tom03es]

I think you need a BIGGER roof rack..........

 

[proteCHE]

about 30-33 mpg bone stock (except for the custom dent job)

I do almost all of my driving in town getting about 30-33 mpg, depending on my mood and the weather. I usually shift at different points for different gears: to 2nd ~2800, 3rd~2700, 4th and 5th ~2500. In the winter I usually lower all of those by about 100 rpm due to the denser charge seems like the engine can handle it better. I plan on installing those extended reach plugs as soon as I get a chance. When I really get some money I want to put a low boost turbo on, tune it for mileage and get a taller tranny.

 

[drivethruecp]

I think you need a BIGGER roof rack..........

...constructive

All this is well and good. But remember it's a big tall OD gear that usually yields mpg. Short of tranny mods, upping the tire diameter within the usable range should help some. (Note: The 'observed' mpg is best with undersized tires - i.e, if 5% too small diameter, your "m" in m/g is really only .95 mile, giving you fictitiously high mpg. Similarly, with slightly over-diameter tires, your 'm' will be over a mile - so your actual mileage is better then that indicated.)
I'm thinking if you were 3% undersized to start with and go to 3% oversized you can get half the gain, or 3% in mileage - about 1 mpg. The other 3% is devoured by the increased engine load (i.e. decreased intake vacuum)

Interesting and well stated! ^

My last 3 fill ups have been 24.7mpg, 25mpg, 24.9mpg, just terrible...

 

[323]

i used to log how many mpg's i got. i dont do much highway driving at all. heres a few:

25.2
23.1
25.4
25.8
27.7
26.7

 

[drivethruecp]

That was mostly mixed, 75% hwy 25% cty guess-timate

 

[Tom03es]

...constructive

So is this thread. You claim to want to improve gas mileage by ANY means, yet you're sporting a big roof mounted bike rack, still running the factory alloys (which have spokes that create drag and you're probably running a 195 wide factory tire), still have the rear deck lid spoiler..............

 

[autoxes]

I just calculated the mpg for my last tank, 35 mpg. Shifted at 2500, injen cai, thermal r&d exhaust. I didn't take it over 3000 that whole tank. I got into it coming out of the gas station, took it to redline, and it felt like a beast!

Conclusion, while it is fun to save gas, it is more fun to drive the hell out of it.

 

[proteCHE]

also, i added some "octane booster" from STP. this car has almost 36,000 kms on it and i don't know if it has ever had any treatments or anything. honestly, i had a hard time deciding which to buy - fuel treatment, octane boost or the other one.[/QUOTE]

Actually, unless you are knocking, octane boosters actually hurt gas mileage. For economy, the best situation is where detonation is just about to happen when the spark goes off. that is why engines that run on compression alone (diesels) are more efficient.

 

[proteCHE]

All this is well and good. But remember it's a big tall OD gear that usually yields mpg. Short of tranny mods, upping the tire diameter within the usable range should help some.

How much do these tranny mods cost? I dream if a 6 speed manual with a hugely tall 6th (2200 rpm at 75 would be cool) and the rest of the ratios just like my stock LX, which I feel are ridiculously short. Does anyone know what this kind of thing would run. I already went through the tranny section and didn't see anything of too much interest. Alternately does anyone know if I could just get a taller final drive. That would up all of the ratios and I would get a small turbo that spools up fast to give me some good torque.

(so many dreams, so little time and money (screwy).)

 

[RABID_MP5]

Hey another thing on this is disk brakes. They rub by their nature, and 4-wheel just doubles the drag. I like to feel the relative heat of the wheels after a trip, with little braking at the end of it. You can buy a temp reader (infrared I think) for maybe 100 bucks to do this better. Another idea to check the front ones is after going a block or more without braking, come to your driveway and brake with the handbrake only. Then jack her up and spin the front wheels by hand to see the typical drag you are dealing with. Caliper piston/cylinder and floater pin maintenance has gotta be the key here. Save on pads & rotors as well.

 

[leetpcguy]

I've got 34.9 MPG on my Mazdaspeed protege. Only mod was the Corksport Exhaust. I drove it very cautiously. Strangely, my gas mileage has gone down since the temps have lowered.

 

[autoxes]

Here's an idea for gas mileage, swap your big wheels, for some 15's. Alot less mass.

 

[autoxes]

I've got 34.9 MPG on my Mazdaspeed protege. Only mod was the Corksport Exhaust. I drove it very cautiously. Strangely, my gas mileage has gone down since the temps have lowered.

Winter formula gasoline will do that until the ecu readjusts.

 

[BinoMP5]

if your desperate... ever heard of Hyper-miling?

or you can boost your car and not hit the boost... but what's the point of that

 

[drivethruecp]

I just calculated the mpg for my last tank, 35 mpg. Shifted at 2500, injen cai, thermal r&d exhaust. I didn't take it over 3000 that whole tank. I got into it coming out of the gas station, took it to redline, and it felt like a beast!

Conclusion, while it is fun to save gas, it is more fun to drive the hell out of it.

I tried that last year at 2300 with no luck. If I remember correctly my economy was a little worse...? I don't recall...