I just got back off my 6500 mile trip in my RX-8. I had lots of time to evaluate this and that.

Here are my concerns and complaints:

Heating of the feet is not comfortable. Too much air is put to the back seats. There should be an option to close a damper for the back vents.

Cycling of A/C when hot outside (Going to address with dealer)

MPG is low. The best I came up with was 23.1 mpg at 60-65 mph.

Intermittent oil light at 80-82 mph. (Going to address with dealer)

Speedo out of calibration This is my biggest complaint of all. I calculated numerous times while on my trip to verify the accuracy. The speedometer is not accurate (verified by about two mph via those construction area radar guns that tell you how fast you are going) and have calculated the odometer error based upon mile markers (performed 8 times in different parts of my trip). The odometer is off 1/10 of a mile for every 6 miles driven. With this information, you can calculate the following:
6 miles = 1/10 mile error
60 miles = 1 mile error
600 miles = 10 mile error
6000 miles = 100 mile error
60000 miles = 1000 mile error

With this information, it appears that for every 60.02 cars that Mazda sells, they are able to negate one car with warranty at the end of 50000 miles. To me, this is a problem that needs to be addressed and fixed. In reality, I am only getting 49167 miles of an actual warranty.

Don't get me wrong, I love this car. There are alot more things that I like than dislike. But I feel that the odometer/MPH issue should be resolved. I will keep you guys posted as to my progress.

I can understand most of your complaints (I need a new oil pan as well), but the mpg you got was great. I've gotten at most 25.5, and that was ONCE. Most of my highway average around 22-23. I think you need to drop that off your list of concerns :).

"Heating of the feet is not comfortable. Too much air is put to the back seats. There should be an option to close a damper for the back vents."

I put duct tape over the back seat outlets, which are under the seats. The airflow to the front footwells increased significantly.

how much is the speedo off by?


EDIT:
oops, never mind
________
Medical cannabis seeds (http://marijuanaseeds.org/)

Originally posted by Magnesium
Speedo out of calibration This is my biggest complaint of all. I calculated numerous times while on my trip to verify the accuracy. The speedometer is not accurate (verified by about two mph via those construction area radar guns that tell you how fast you are going) and have calculated the odometer error based upon mile markers (performed 8 times in different parts of my trip). The odometer is off 1/10 of a mile for every 6 miles driven.

:confused: First, speedometer - it's against federal law for a vehicle to indicate slower than it's actually going - so EVERY manufacturer that sells in the US calibrates their speedometers to indicate very slightly faster. 2 mph at highway speeds (as many of us have already found and posted) is more accurate than many vehicles on the road, and certainly within allowable tolerances. Nothing will be done (nor should be done) about this.

Second, odometer - just what sort of accuracy do you expect? It's within 1.7%!!! Again, well within required limits! Don't bother, there is nothing that can, will, nor should be done about this.

Regards,
Gordon

I wasn't aware of the laws.... I will enquire when I take it in for scheduled maintenance and see what they say.

Sounds like what I have been saying for a while, that the speedo and/or odo are wrong.

PS, did you also notice that the trip ODO is off from the main ODO? It's about 1 mile off for every 2000 miles driven...

Originally posted by DisneyDestroyer
Sounds like what I have been saying for a while, that the speedo and/or odo are wrong.

PS, did you also notice that the trip ODO is off from the main ODO? It's about 1 mile off for every 2000 miles driven...


These concerns are very interesting and informative, but in my opinion, extreme nit-picks.

"First, speedometer - it's against federal law for a vehicle to indicate slower than it's actually going - so EVERY manufacturer that sells in the US calibrates their speedometers to indicate very slightly faster. 2 mph at highway speeds (as many of us have already found and posted) is more accurate than many vehicles on the road, and certainly within allowable tolerances."

Funny. I have a Benz that has both analog and digital and the digital is 2 mph faster than the analog. Benz tells me the digital is more accurate since it's entirely electrical versus the analog which is electro-mechanical. That said, I don't think the highway radar signs are necessarily all that accurate. If they were, cops would be using them to write tickets and I never heard of that being done. So, on another note, if anyone thinks the 8's speedo is off, check out someone who owns a BMW 3 Series. Even the M3 is notorious for its highly optimistic speedo. I've read that it's as much as 10 mph faster at 80 mph than it is really going! And the ODO is always going to vary a little depending on tire inflation, wear, etc. (as will the speedo). Oh, and if the oil light comes on, even intermittently, you're maybe 1 qt. low...that's halfway between the marks on the dipstick. Add oil. I've used about 2 qts. in 2700 miles. Rotary engine use oil to operate properly.

Please don't drop the mileage complaint when talking to Mazda. You reported a best of 23.1 at 60-65, presumably out of many road tankfuls on a 6,500 mile trip. That is a very modest pace, at which you should get better than the EPA 24. My average of three tanks on a 750 mile road trip was 22.5, vs. the 25 EPA for my AT. City mileage is also 2/3 mph under the EPA number. That shortfall add$ up.

Between the construction area radar gun, the highway mile markers, and the RX-8's speedometer/odometer, I'm not sure you could really say which one is more accurate than the others. I think you have just as much basis (i.e., not much) for claiming that the highway mile markers are not spaced correctly! Maybe this is a government public works problem!

Yes, all speedometers read a touch low, they aren't allowed to read high, so the automakers do a bit of known "error"... IIRC european cars are especially bad at this...

Wasn't there a thread where someone checked the speedometer w/ GPS, and found that it was actually pretty close?

Yep, I found that mine was within 2% all the way to triple digits, when compared to my GPS.

Originally posted by Magnesium
Speedo out of calibration This is my biggest complaint of all. I calculated numerous times while on my trip to verify the accuracy. The speedometer is not accurate (verified by about two mph via those construction area radar guns that tell you how fast you are going) and have calculated the odometer error based upon mile markers (performed 8 times in different parts of my trip). The odometer is off 1/10 of a mile for every 6 miles driven. With this information, you can calculate the following:
6 miles = 1/10 mile error
60 miles = 1 mile error
600 miles = 10 mile error
6000 miles = 100 mile error
60000 miles = 1000 mile error

With this information, it appears that for every 60.02 cars that Mazda sells, they are able to negate one car with warranty at the end of 50000 miles. To me, this is a problem that needs to be addressed and fixed. In reality, I am only getting 49167 miles of an actual warranty.
All this sounds very scientific but....

1. Those construction sight radar guns are notoriously inaccurate. They are there simply to remind people to think about how fast they are going compared to what the speed limit (much like the effect that video cameras and tv's showing you walk into a grocery store have in keeping people from shoplifting).

2. Have you ever thought of who placed those milemarkers? Do you think they were terribly concerned with the fact that people will be performing scientific studies with them? I can't see them out with a ruler making sure they they were all placed in the perfect spot.

I'm not saying that there isn't a possibility that our spedo's and odometers are inacurate but that you have to use better methods of proving it.

Also, if this is the biggest thing you are upset about....WHAT A GREAT CAR! :D

Originally posted by Elara
I can understand most of your complaints (I need a new oil pan as well), but the mpg you got was great. I've gotten at most 25.5, and that was ONCE. Most of my highway average around 22-23. I think you need to drop that off your list of concerns :).

You kidding? How did you get 25? My car, and with many people's around here, the poor things only get below 20mpg.

I have Blue RX8 (not that the color matters), GT package with Nav system. I have light loads with a package, cleaning stuff/extra oil quart, and myself in the car for most part. Once a while a tag-along passenger. I live and drive in sunshine California with a bit of hills (No, not SF kind of radical hills). I am babying the car big time, keeping rpm around 3000, barely touch 5000 if I do acelerate, avoid next door commuting as much as possible (commuting .05 miles away). And local only, I get 15.5mpg on average. And when I do freeway cruising (driving from LA to SF), I get 18.7mpg.

Typically, my best mpg (highway only) is from full to E, I could crank in around 260 miles within that 13.9 gals. I have done it 3 times, with my total mileage up to 7200 miles driven so far.

Originally posted by eccles
Yep, I found that mine was within 2% all the way to triple digits, when compared to my GPS.

Can you post more info regarding your finding later on? I will monitor this with my GPS too. But where I live I have some hills so it won't be too accurate whereas the altitude will make the distance longer than it shows on GPS (which presumes all land is flat). The GPS is still using 2D system.

Originally posted by starstar5
Can you post more info regarding your finding later on?Tested against my Magellan Map330 handheld GPS mounted in a dashboard cradle. At 70mph indicated, the GPS speed was 68.9mph; at 100mph on the clock, the GPS said 98.7.

That is prety much my discovery using a hand held GPS. I consistantly read 2-3 mph slower on the gps than the speedo. So 70 on the spedo is a gps 67 or 68. 80 is 78ish. I sort of think of it as cheap insurance. I think I'm doing 85 (speed limit 75) and I am only really going 82. Cheap thrills I know, but maybe the cops will be less likely to nail me for doing 7 over the speed limit versus 10.

I thought it was just my car but as I see many of the 8 are having the speedo problem. I knotice it with in a month. Wend the miles register was almost 1k in one month and all I was driving was to work and back. (55-60 miles) with just one trip of about 60-80 miles in the same state Fl. I told my service rep and spoke to the General manager. They did not take my word for it. Im going to let them know my new findings.:confused:

Originally posted by mxmedina
I thought it was just my car but as I see many of the 8 are having the speedo problem.

I don't know what problem you're having, but what we're all saying here is that a slight variation from actual is normal - the numbers being talked about in this thread are normal and reasonable, NOT a problem!

Regards,
Gordon

I agree.
The numbers that you guys are posting are 2% or less. This is pretty typical of vehicles.

BTW, mxmedina.
At a 2% variation, that is only 20 miles over 1K. Can you honestly say that you didn't drive the additional 20 miles over a month? Your guestimate of your typical comute varies by 10% (you said 55-60 miles).

I know I am putting way more miles on my car than on previous cars. But that is because I..
1) Take all the twisty back roads.
2) Look for every excuse possible to drive.

I'm sorry, but I have a problem with this in principle. Mainly because the advantage is all Mazda's, the disadvantage all mine.

1) The warranty is for fewer real driving miles than they claim. That means that Mazda has to support the car for a shorter period of time, and I am responsible for the car's problems sooner.

2) The cars' average miles before breakdown will be larger than in truth, giving a falsely inflated public impression of the vehicle and company.

3) When I go to sell the car, there is a slightly lower resale value due to inaccurately added mileage.

4) I spend more $$ on oil changes and maintenance, or spend the money closer together.

Originally posted by DisneyDestroyer
I'm sorry, but I have a problem with this in principle. Mainly because the advantage is all Mazda's, the disadvantage all mine.

1) The warranty is for fewer real driving miles than they claim.

Your warranty is for odometer miles, not actual miles (however they might differ). There is no other way to measure, is there? Even a GPS doesn't properly record distances when significant elevation changes are involved. Would you seriously suggest that people who regularly do burnouts or spin the tires on snow/ice should have a warranty adjustment to compensate for the odometer increase in mileage when the vehicle didn't actually travel those miles? How do you suggest Mazda should be compensating for tire wear, since of course as your tread wears, the tire becomes shorter in diameter, introducing more discrepancy between actual and indicated mileage?

This isn't a Mazda problem, it's common to EVERY VEHICLE ON THE ROAD. Odometers have legal precision requirements, and that's all - they are not required nor expected to be exact, just within a certain percentage.

If you really feel that your car is going to fall apart in the final 800 miles before warranty expiry and you might just miss out on warranty coverage (dang it, where is that rolleyes smiley when you really need it?), consider that most manufacturers will provide warranty coverage of a failure if it occurs just outside the warranty period (ie within 1000 miles or 1 week of warranty expiry).

Regards,
Gordon

Originally posted by DisneyDestroyer
I'm sorry, but I have a problem with this in principle. Mainly because the advantage is all Mazda's, the disadvantage all mine.

1) The warranty is for fewer real driving miles than they claim. That means that Mazda has to support the car for a shorter period of time, and I am responsible for the car's problems sooner.

2) The cars' average miles before breakdown will be larger than in truth, giving a falsely inflated public impression of the vehicle and company.

3) When I go to sell the car, there is a slightly lower resale value due to inaccurately added mileage.

4) I spend more $$ on oil changes and maintenance, or spend the money closer together.

Have you ever done this test before, or are you just this obsessed w/ your new car ;)?

Every car on the road has these issues...
Heck, if you're that concerned about it, switch to a higher-radius tire, you can cheat mazda! :eek:

Originally posted by DisneyDestroyer
I'm sorry, but I have a problem with this in principle. Mainly because the advantage is all Mazda's, the disadvantage all mine.

1) The warranty is for fewer real driving miles than they claim. That means that Mazda has to support the car for a shorter period of time, and I am responsible for the car's problems sooner.

2) The cars' average miles before breakdown will be larger than in truth, giving a falsely inflated public impression of the vehicle and company.

3) When I go to sell the car, there is a slightly lower resale value due to inaccurately added mileage.

4) I spend more $$ on oil changes and maintenance, or spend the money closer together.

I have an easy solution for you...
Go look up different profiles of tires (the online places list all the info as far as tread width, tire diameter etc).
Find a tire that is slightly larger in outer diameter, probably will be slightly wider anyway. A slightly larger diameter tire will travel further per revolution. Try to find something about 2 or 3% larger in diameter if you want to be close, or go larger if you want milage to underreport slightly.

A quick check show that 245/45/R18 should fit. They have almost exactly a 3% greater diameter, and .6 in wider footprint.

:grin: thanks for the info, but it doesn't solve the larger problem of inaccuracy.

Originally posted by DisneyDestroyer
:grin: thanks for the info, but it doesn't solve the larger problem of inaccuracy.

There is no problem of inaccuracy. The odo is well within specifications, both design and legal. It isn't meant to be perfectly exact, and couldn't be even if they wanted it to be (unless you want your odometer to cost more than the entire rest of the car...).

Regards,
Gordon

Oh. My. God.

Listen to the facts.

Manufacturers cant make 100% accurate speedo's.

Manufacturers cant have the speedo show a speed of less than what the car is mooving at. (i.e. cant show 60 and you realy be doing 65).

Manufacturers set it so it always over reads.

In Europe it can be as much as 5% out and still be ok, and it gets worse the faster you go (in pure MPH terms).

Your speedo may not even corralate to your odometer, who knows, but things are made to tolerances not exactitudes.

Get over it, or go design a cheap, perfect speedo.

There is NO problem of inaccuracy. It is well within specs.

In my opinion, since the stock tires wear very quickly, I plan to get better tires when needed. I might go slightly larger (just because I want wider tires, not to trick the ODO. )

Originally posted by DisneyDestroyer
:grin: thanks for the info, but it doesn't solve the larger problem of inaccuracy.

"Within specs" and "accurate" are two different animals. Please don't try to tell me they are the same. Accurate is black or right, right or wrong. It either is or it isn't. 2% out of 100,000 miles is significant enough (2000 miles) that you can't say it's accurate. 10 feet out of a mile is too much to say it's accurate. It's true that different people have different person opinions of when something is "too off to be accurate". That's why the range provided by regulations is useful here, to avoid legal entanglement for Mazda.

Within specifications and government regulations, sure. Accurate, no.

Originally posted by DisneyDestroyer
"Within specs" and "accurate" are two different animals. Please don't try to tell me they are the same. Accurate is black or right, right or wrong. It either is or it isn't.

Sorry,
There are no absolutes.
Accuracy is never absolute, it is defined within some margin of error.

So, should I assume that you have verified all of your previous vehicles odometers to a level of accuracy that meets your requirement? I assume you did this using some highly accurate device (I would trust a GPS on level ground, but not milage markers).

Originally posted by DisneyDestroyer
"Within specs" and "accurate" are two different animals. Please don't try to tell me they are the same. Accurate is black or right, right or wrong. It either is or it isn't.

Actually, you're very wrong about what defines the term "accurate". If you had studied science or engineering, you would know that it is physically impossible to get 'accurate' as you think - what you CAN define is degree of accuracy, ie acceptable margins of error.

EVERY "accurate" scientific measurement includes a +/- margin of error. You want to measure temperature? It's 75F, +/- 3F on your average household thermometer. If you use a calibrated scientific instrument, you might get 75.395F, +/- .005F.

Even on a racetrack where they use electronic transponders and very fast computers to calculate lap times to .001 seconds (which actually means their lap times are accurate to +/- .0005 seconds), they can't tell you what speed the car is actually travelling, because the exact distance travelled over a lap varies depending on the line the driver takes.

So, your odometer is accurate to +/- 1.5%. If you spent thousands of dollars, you might get speed measuring equipment that's accurate to +/- .1%. You will NOT EVER get speed measuring equipment that has NO margin of error, as you seem to imply. It's impossible.

Moral - give it up, your odometer is perfectly accurate to acceptable legal and practical requirements. Nobody will do anything to change it, and if you make a big fuss they will start laughing at you for your ignorance.

Regards,
Gordon

PS - That's why the range provided by regulations is useful here, to avoid legal entanglement for Mazda. Why do you presume that it's only Mazda that doesn't have odometers accurate to .000000001 feet per mile? The accuracy requirements apply to ALL MANUFACTURERS, not just Mazda. As has been said to you over and over, it's not a problem, and it applies to ALL cars. Why not try to actually learn something instead of being so pig-headed that you make yourself look silly?

I make no presumptions, I have had the same issue with other cars I've had.

I didn't give my car back, etc. because it's not that much of a problem.

Neither changes the fact that it bugs me.

You are never going to get much better accuracy - remember the diameter of the wheel changes considerably with tread wear and tyre pressure. The cars odometer will be calibrated for the average condition of the tyres. So it may get better towards the mid life of the tyre then go back the other way.

Cheers
---Dave

Originally posted by DisneyDestroyer
"Within specs" and "accurate" are two different animals. Please don't try to tell me they are the same. Accurate is black or right, right or wrong. It either is or it isn't. 2% out of 100,000 miles is significant enough (2000 miles) that you can't say it's accurate. 10 feet out of a mile is too much to say it's accurate. It's true that different people have different person opinions of when something is "too off to be accurate". That's why the range provided by regulations is useful here, to avoid legal entanglement for Mazda.

Within specifications and government regulations, sure. Accurate, no.


Dude, you gotta be kidding me if you were planning on getting 100% accuracy in speedo and odo? lol. There is not mazda, honda, toyota, nissan, chevy, ford, mercedes, bmw, audi, vw, dodge, or any other car that's affordable that is actually 100% accurate in odo and speedo. Just deal with it. Wow, 2000 miles out of 100,000 miles is really big deal. If your selling a car, and u say it has 100K or 102K, it wont make a big deal. It's basically a same thing. Unless at 100K miles, your car will actually only have 90K miles, then there is no problem you should worry about.

If you're getting accuracy under 2% stop complaining. Sheesh!

Construction radars are typically off-axis due to their short range. That means they suffer from something called cosine error causing them to read a tad low.

Small percentage changes in tire diameter can come from pressure and load. That means things like temperature and the number of passengers will affect the number or revolutions per mile and affect accuracy.

Your mileage is excellent - especially cosidering EPA highway ratings are done at 55 MPH IIRC.

If you want someone to blame for spedos being biased slightly to the high side, blame class action lawyers and the government. If Mazda calibrated them dead nuts, there would still be a few that read slightly low. Enter some class action scheister to sue Mazda for millions claiming some percentage of spedos induced their drivers to speed by reading low. After he skimmed 99% of the settlement for his fees, we would get to split the remaining 1% 40,000 ways. Of course, Mazda would factor the legal costs into its product and we'd all indirectly pay.

Originally posted by newport8
Between the construction area radar gun, the highway mile markers, and the RX-8's speedometer/odometer, I'm not sure you could really say which one is more accurate than the others. I think you have just as much basis (i.e., not much) for claiming that the highway mile markers are not spaced correctly! Maybe this is a government public works problem!

I work for the WASHINGTON State Department of Transportation. Transportation departments consider mile post markers addresses, like a house number.

They are not accurately placed.

Many times the path of the roadway will change, changing the distance, but they do not relocate the mile post markers. Think about it. Personally, I would not even trust the "test mile post markers" you sometimes see around.

Your speedometer is likely accurate within reasonable tolerance.

And if no one here knows it, even police radar is not 100% accurate. Each officer is required to be trained and the gun calibrated for each daily use. And, according to some officers i know, except maybe in a school zone, you will get a 10 mph leaway, e.g., they won't write a ticket unless you are 11 mph+ over the posted limit. I'm sure there are numerous tales about getting stopped at lower speeds, but that's a product of the local revenue collectors. My complaint is that they don't write tickets for people going more than 11mph LESS than the posted limit!

Originally posted by Gord96BRG
There is no problem of inaccuracy. The odo is well within specifications, both design and legal. It isn't meant to be perfectly exact, and couldn't be even if they wanted it to be (unless you want your odometer to cost more than the entire rest of the car...).

Yes, I'm thinking an inertial navigation system would work nicely :)

As other posters have mentioned, if it really bugs you; switch to larger tires to compensate. As the OEMs will certainly be done for by 20,000 miles you'll have plenty of chance to recoup before the warranty expires.

Originally posted by DisneyDestroyer
"Within specs" and "accurate" are two different animals. Please don't try to tell me they are the same. Accurate is black or right, right or wrong. It either is or it isn't. 2% out of 100,000 miles is significant enough (2000 miles) that you can't say it's accurate. 10 feet out of a mile is too much to say it's accurate. It's true that different people have different person opinions of when something is "too off to be accurate". That's why the range provided by regulations is useful here, to avoid legal entanglement for Mazda.

Within specifications and government regulations, sure. Accurate, no.

Your idea that accuracy is a binary condition isn't true. It's not a matter of opinion - there is no perfect accuracy even with the finest instruments. I imagine you could measure the distance accurate to within angstroms - but that scientific instrument would come with specifications saying something like "accurate to within +- 4 angstroms per mile" or some such, and there would be many other considerations as well. how will you measure the distance - what part of the road will you use? How many times will you change lanes? Which tire's rotation is "accurate" - they will all be different! What about the elastic deformation of the tires? How many times will you run over road stripes? All of these variables add up. In the world of scientific measurements this type of thing results in measurements that are given in terms of "significant digits". For example, if the measuring instrument is accurate only to 1/100 of a mile per 600 miles, your fancy odometer reading of a long trip might say 600.0247 miles. However that number is not reliable and you would have to limit the measurement to 5 significant digits - 600.02. Similarly, the other error factors all impact the quality of measurement and could further reduce the number of significant digits you could claim as "accurate".

Don't even get me started on Fractal Geometry -- but consider "what is the length of a coastline"?

I can't beleive that there are people like this......its truely amazing....

Originally posted by RXTACY
I work for the WASHINGTON State Department of Transportation. Transportation departments consider mile post markers addresses, like a house number.

They are not accurately placed.

Many times the path of the roadway will change, changing the distance, but they do not relocate the mile post markers. Think about it. Personally, I would not even trust the "test mile post markers" you sometimes see around.

Your speedometer is likely accurate within reasonable tolerance. My point all along. Those who are upset about the inacuracy of their spedo's, how are you using something that is inacurate (the mile markers) to measure accuracy :confused: Even GPS is not 100% accurate. I know because I use them all the time....I'm a pilot.

I do however remeber seeing Calibrated mile markers on some hiways. They had signs that said they were calibrated for verifying your speedo/odo.

Don't know how accurate they were, but they were probably better than the typical mile marker.

You guys are measuring spees and MPG to the .1 unit? Do you realize that the accuracy the measuring instruments you base your conclusions on are not within the precision of your data analysis? In other words, car speedos do not measure within +- .1 mph. Just getting within 5% would be reasonable.

Concern over missing another 800 miles of your warranty over this? Get real! Nothing is guaranteed in life. And as far as MPG concerns, welcome to the rotary world! I'm gettin 18 on my less powerful and lighter 87 RX7 during normal daily driving.

You either love the rotary or buy a 350z, or some other clone.