Gas mileage: Must be my driving

[WaatDaHell]

I purposely drove like an old lady on a trip this week. I got 295 miles before the light came on. Sad.

Damn, I hate having to drive like an old lady. It was so difficult for me to do the same thing, but I still got 320 miles. I just decided to drive like a maniac and get 290 instead. At least I get to "feel" the P5. Regarding the nos issue, my bro had an idea that made sense. Dentists use the same chemical the the nos system uses. So it should be cheaper to get it from the same peeps as the dentists do. I really don't know about it cuz he's the mechanic not me. Oh well, I'm not there yet so we'll just see. He said the system he has is actually very economical because he sets it at a certain rpm for it to kick in, which is not until I really get psychotic or when some Dude in a Civic keeps gawking at me and wants some trouble. This is a good thing cuz I don't want to get too many tickets from those motorcycle jerks. That doesn't help debts.

 

[Protege01MP3]

ok.. the dentist thing.. yah.. same chemical... but i really doubt its the same mixture and balance of chemicals in those bottles as the NOS bottles for cars... you MIGHT get it cheaper.. but you also probably need a dental license to buy it, and it may not be the exact right compound...

and WTF!!! thats nutz.. y would anyone set NOS to kick in at a certain RPM!!... you have any idea how quickly your supply will deplete?!?!?! and what if your in traffic and finally get moving a little.. still kinda bumper to bumper.. but enough to move... then your in second gear.. not flooring it.. just cruising along... all of a sudden you hit 5500 RPM and before you know it your car is wedged in the hatch-door of an RX300 or BMW X5 and you'r paying for all their damages...

just use a button.. and press it whenever the hell you feel like

 

[Gyre]

I've seen N20 kits that go on at RPM AND WOT. Just RPM does sound a bit dangerous but if you're flooring it you probaly want all the power you can get.

 

[Protege01MP3]

yah... ok.. that makes more sense... if your flooring it and hit 5500 rpm you probably are trying to pull as much power out as possible.. so I would agree that the combo of a certain rpm level AND wot would be a kinda cool setup.. still a little dagerous... but nice nonetheless....

thx for pointin that out gyre

 

[WaatDaHell]

I don't know the exact detail cuz I don't know much about it to begin with. He said it works kinda like the hybrid systems on the Hondas. You don't really know it's there but you do know there's a difference in power. Nothing's happened yet so we'll see.

 

[Protege01MP3]

maybe its an EXTREMELY EXTREMELY minimal amt. of N2O being mixed into the air/feul mixture??? that way it wouldnt give much of a boost... it would just be almost like putting higher octane gas in the car... in theory

not sure how NOS works exactly.. i know the basics but im not a NOS tuner or anything.. so i dont know whats theoretically possible, whats been done, what is possible or what is crazy as hell and would never work... but the above sounds like it might work to me...

 

[lorden]

WHOAAAAAAAAAAAAAA do i hear you guys saying 400miles? i am in canada so we do KM, and i do about 300-350 KM per tank.... obviously not normal, that must be about 280miles per tank

 

[azeli73]

I mostly do city driving and get around 300 a tank. If I venture out on the highway, I'll maybe pull 340-350. Not bad compared to my last vehicle. A 88 Toyota 4x4 that got 10-12 mpg.

 

[Tonpow]

How fast on the highway?

 

[azeli73]

How fast on the highway?

Average 75 to 80... Arizona highways are stright. So are all the streets... DAMN I HATE THAT... Have to drive up north for curved roads

 

[Don]

Generally I think most would agree that the P5 is generally lousy for gas mileage on the highway if you compare it with other cars that have a similar size engine and are approximately the same weight. I believe that this is because the P5 engine's top gear runs at annoyingly high RPM's. I'm sure if Mazda made the 5th gear run at lower RPM's we wouldn't all be complaining like this.

I guess it's all in your perspective . . . . and the "other car" you're comparing it too.

My other car is a Miata, with a rear end ratio of 4.10 to 1, so that's 4100 RPM @ 75 MPH on the freeway (earlier 1.6 Miatas have a 4.30 to 1 gearset in back). I'm not sure what the gearset in the P5 is, but it must be somewhere near 3.70 to 1, just based on the differences. My Miata (which is several hundred pounds lighter than the P5, plus has a smaller 1.8 engine) gets me 28 or 29 on the freeway at 75, while the P5 (even loaded down) gets me 30 or 31. So, complaining? - NOT ME!

You wanna hear "annoyingly high RPM's" on the freeway? - I'll take you for a ride in the Miata!

Don

 

[Tonpow]

I have NEVER reached 30 MPG. Even driving like a saint, no extra load, slow starts, 95% highway pegged at a steady 65MPH.

29 is my highest. It took an all out MPG assault to reach that number.

I average about 25-26MPG with 95% highway. I can live with it. But it is pretty wacky and I'm fascinated by it. Like I said. My V6 Jetta averaged 29 driving the same rout. That's with a bigger motor, 40+more hp, about 600 pounds more heft, and a trunk often loaded with junk. Everything you read and those pesky laws of physics don't line up with the results. Cars that are 500-1000 pounds heavier, have larger motors etc...should be at a disadvantage in the MPG wars. On paper, the Protege should have no problems reaching over 30 when compared to other cars even out of its class.

I have a feeling that Mazda cheaped out with the ECU and the amount of time spent fine tuning it for the best efficiency. In the interest of cost and time constraints, they probably took the safe rout and went overly rich in most conditions to fight detonation and get decent performance. It would be interesting to see what A/F ratios the car runs at steady cruise and how much time the car spends closed loop. The strategy and reaction time of the ECU is very important when it comes to MPG.

I'm getting a wideband O2 meter soon for other tuning projects. I'm very interested to see what kind of A/F ratios the car sees in average conditions. I'll post results as soon as I get them.

 

[fastdrvr23]

I figured I would add my updated mileage log in case someone wanted to compare or something...It might show up strangely due to my webspace, if it does, just hit refresh.

Mileage Log

 

[LA dreamer]

It seems as though roughly half of the P5 owners get great gas mileage and the other half of us don't. Perhaps we got the cars that weren't as well put together for some reason. I don't know why else there would be so much disparity.

 

[Tonpow]

Yeah. I was just contemplating that one too. Maybe 01 Vs 02 model years? Maybe they made a programming change?

Maybe some motor assembly issues? Maybe some of us have birds nests or a big gob of casting flash in our manifolds?

Maybe a bum batch of 02 sensors?

Once on my wife's car a routine sparkplug and wire change went horribly wrong and I damaged the primary O2 sensor.(long story) Her mileage went from 20city 30 highway to 13city 22highway.

That thought in mind I may try a new 02 sensor for the heck of it.

 

[kenbob]

Well, I'll throw my pennies in. My MP5 automatic has only gotten better than 25 mpg on one tank, and that was about 27. On that tank I filled up just before getting on the freeway and filled up again at the other end. Most of my driving in highway between Houston and Austin, I drive 70-75 mph, and lately haven't been using the AC. My last tank was 23 mpg. That SUCKS! I have a friend in Houston with the same car and his mileage sucks also. Another friend in Austin has a 5 speed MP5 and he gets 31 on the highway, 28 average.

I've talked to Mazda USA and my local dealer to no avail. They just keep telling me that the number on the sticker are an estimate. I keep telling them that a Mustang GT gets better mileage with twice the horsepower and 1000 pounds more weight. The automatic and manual cars are geared identically in top gear, so when the torque converter is in lockup the only difference is hydraulic pump losses. That might be worth 1-2 mpg, but not 6. Most likely the problem is the ECU fuel and timing maps for the automatic. I hate litigation but I'm going to pursue a class action on Mazda if they can't rectify my mileage or swap me for a 5 speed. So far there's two of us here in Houston. If anybody else is as p.o.'d as I am, let me know.

Depending on how many miles you drive, you'll spend as much as $200/year extra in fuel compared to what the car was advertised. Additionally, the advertised mileage is pretty poor compared to other cars in it's class, i.e. 2.0 liter 130 hp 2600 pound cars like the Focus.

 

[kenbob]

One other thing. Anybody that says they're "not real happy with the mileage but it a lot better than the X mpg they were getting in their (fill in the blank tank)" is missing the boat here. Just because you were driving a Hummer getting 8 mpg doesn't somehow make a Geo Metro getting 25 mpg acceptable. A given car of a given size and performance/power level should get a certain fuel economy when driven a certain way. If that's not happening, there's an engineering or mechanical reason for it.

 

[Tonpow]

update

I got 25 and 26 out of my last two tanks.

 

[Tonpow]

I agree. I love the car. I'm happy with it.

But. Big but, you are 100% correct. There has got to be a fundamental reason.

The 25 MPG best defies the laws of physics and comparison to similar cars. On paper, this car should have no problem reaching 30+ with nice driving habits. 25 and lower should be for the jack rabbit city drivers and the speed demons.

Gearing?
ECU programming?
Engine design and tuning?

Who the heck knows. I wounder what the Probe with the 2.0 gets for MPG?

 

[Humvee]

Lorden I hear ya on the mileage. I've got an auto, city driving I'll do 400km on 50L. My 93 std civic would give me 450-500km on 35-38L!

I love the new car...I guess that's the price we pay.