BruceInColorado

and Voila! You will have a screen representing the wiring systems monitored by your GPS(!)

The bar labeled "Speed" is what we are all talking about. I took this while the car was sitting in the driveway, so it doesn't show the yellow bar that moves horizontally across the "speed" bar - supposedly indicating your speed. (If I got pulled over for just messing with it while driving, think about the ticket I would get for taking pictures while driving!)

BruceInColorado

This is what you would have gotten had you clicked "GPS" instead of "Wiring Check". Pretty cool - it tells you all the satellites that you GPS is currently using for positioning and where those satellites are positioned above Earth. The "*****" representing the satellites even move across the image of the Earth as the satellites move. It will even show when a particular satellite becomes active or inactive for positioning to your GPS.

BruceInColorado

Finally, here is another bit of information that one of the backdoors will tell you - the version of your software. Looks like I probably got an older version (I think I hear the Mazda vacuum sucking more money out of my wallet for the "newest" version of NAV software!) Does anyone know the "newest" version?

So, one thing I was thinking: The "Speed" indicator on the Nav system (see previous pic) that we are talking about... as I said, it is not accurate. For example, it is consistently "low" and certainly lags behind by several seconds as you change speed. Is this because it is actually obtaining its reading from the satellites and not my car (speedo)? It really wouldn't be that far-fetched: The satellite knows - and feeds my GPS info about - where the car is and where it is moving, therefore it knows how fast it is going. The time-lag (i.e., I speed up to 65, but this NAV speed indicator takes a few seconds to climb up to 65) would make sense, because it takes a few seconds for the signal to go up to the satellite(s) and back to my system.

I dunno, but it wouldn't seem that difficult for anyone to monitor where you are (or how fast you are going) from satellites - at any time!

Big brother is watching!

JSE RX-8

thanks for the pics...good work

Boozehound

Interesting... Bruce you must have the newest firmware. I'll go tinker with mine later this afternoon, but I don't get any fancy-schmancy car picture in my backdoor (wait, that didn't sound good). I don't believe there's a wiring check that's accessible through the hidden menus on mine. I'll go play with it after work, but I'm wondering what else mine doesn't do...

As for big brother watching... your car would have to transmit something back to the satellite for it to know where you are. And unless there's a big conspiracy going on <looks around suspiciously>, your car shouldn't be transmitting jack. Just like radio, you pick up the signals broadcast out over everywhere.

Boozehound

Ok... so I'm simple. I found the other two menus last night on my car. I had previously thought there was only the one, but lo and behold there are others. Cool.

BruceInColorado

Boozehound - let me know what you think about the accuracy of the Nav Speedo (and if you think my guess is right that the satellites are measuring your speed, rather than internally.)

But seriously, make sure you take a passenger along while you mess with that - it's too easy to get distracted from the road while your eyes are darting back & forth between two speedos!

Boozehound

Between the two Nav speedos, they both seem slow compared to what the actual gauge shows. The bar graph is hard to read, but the the other nav speedo (in km/h) is much easier to compare when you switch your gauges to metric. You were right about the update speed for the bar graph, it sure seems slow to refresh (probably only updates once a second).

I don't know if one of the two nav speedos is reading what the car is sending it, or what the satellites are providing. If I had to venture a guess, I'd say that the satellites provide data for the bargraph (b/c of the slow update) and the other may be the car - but I could be totally backwards.

bwayout

Here's the image I believe your referring to ...




I believe it originally was show last year in a special Road & Track RX-8 edition what was only available to their subscribers. When I went to last year's Rev-It-Up event, I got the same mag but without this picture.

Just last weekend I was at this year's Rev-it-up and went over to the Mazda Speed RX-8 display tent – but sadly, no one there had any idea of what I was talking about.

BruceInColorado

Hey, that steering wheel is on the wrong side!

Well, you can tell that the image wasn't photoshopped in - so *somewhere* someone has devised a nav-speedo. Although I have no way of verifying this, it looks like this is a non-functional mock-up. It *looks* like you can discern stationary objects outside in the background - no more than about 50 yards away. It is my belief that you couldn't get a car going 128kph (80mph) and take a (digital) picture without the background being a complete blur.

However, if someone tried hard enough, I don't think it would be impossible to customize this kind of speedo. I'm surprised that someone hasn't already done it. I'll do some research and anyone else interested should do the same... and we'll all meet up later and compare notes! :-)

Pavehawk

That's not a speedometer. It looks like oil pressure and oil or water temperature.

bwayout

True!

We just need Mazda (or someone else) to some up with this that also includes a voltage/battery digital gage too!

:D

BruceInColorado

I don't know how they do it where you're from, Pavehawk. But my steering wheel is on the left side of the passenger compartment! (Just kidding with ya... You didn't know I wasn't talking about the nav guages with my first comment)

Take a look at the pic again - the steering wheel and instrument cluster is on the right side - so that must mean that the RX-8 pictured is not from North America. All the stereo controls are in English, so maybe this was in Australia or England?

And Bwayout - hear, hear! We could use a real battery/amp guage AND a functioning oil pressure guage. But from what I've read, that would be a huge undertaking, because you'd have to add a different sender unit to the engine block and hack or bypass the emissions sensors.

If somebody came up with all of this (nav speedo, oil pressure, voltage, etc.) I guarantee it would sell in the thousands.

BruceInColorado

Well, from the looks of the graphics, that nav-speedo comes from MazdaSpeed. Here is their website:

http://www.mazda.co.jp/customize/rx-8msv/

If anyone reads Japanese, (or even if you know anything else about them) I'd be curious to know what is available here in the states.

randyrx8

I did a quick test this morning

I drove 50 miles on the Mazda odometer
My Gps trip odomometer said I went 49.0. They may be separate but they seem to be consistant, 2% Faster and 2% more miles.

BruceInColorado

My question is why Mazda would intentionally make either the odometer or the speedometer inaccurate? The insurance answer doesn't fly with me - because in my experience with insurance companies (paying a lot of it!... and former attorney for State Farm & Farmers) I don't think it would make any difference in their underwriting considerations.

One thing does come to mind - if your gps is accurate and said you went 2% less far than your car odometer said, then that means I am getting 2% less gas milage! (right?) I guess that would be incentive for Mazda to be misleading...

randyrx8

I had thought about that, and Another interestiong point would be that the 50000 mile warrenty is now a 49000 miles warrenty.

Boozehound

Are odometers held to a gov't standard? I would guess that'd be the case to eliminate said "shuck'n and a jive'n."

I guess I figured the odo and the nav speeds would be accurate, while the speedo gauge would be reading fast for whatever kind reason they want their drivers going slow... You know I don't think I've owned but one car that's speedometer matched a GPS readout, and it was a Buick Park Ave - outside of it, everything else registered faster on the gauge.

Who knows, when in doubt, blame it on selective availability...

Gord96BRG

This has been discussed in several threads months ago -
for speedometers, it's federal law. Government requirements in most countries (including the US) prohibit a speedometer from indicating a speed that is lower than the actual speed of the vehicle. (ie, it's illegal to have a speedometer indicating 60 mph when the actual speed is 62 mph).

So, ALL manufacturers build in some margin of error on the high side to allow for manufacturing tolerances, etc. Many of us did GPS comparisons and found around 2 mph high indication at ~70 mph, ie indicated 75 mph was an actual 73 mph, etc.

There's no requirement for odometers - they're allowed to be as accurate as possible, and their readings are not linked to any speedometer variance (ie just because your speedo shows high does NOT mean that your odometer will read a greater distance than actually travelled).

Regards,
Gordon

randyrx8

What I was stating today was that I did a test of distance and the Odometer seems to have the same bias as the speedometer, I know one test of 50 miles is not a a gauratee of the data but the fact that it matches at 2%, suggests it probably prbably is acurate.

zojas

selective availability has been turned off for years now.

I was trying to watch my gps this morning on the way to work. too much traffic to get a really accurate comparison between speedo and gps, but it looked like my speedo was between 2 and 3 mph faster than the gps reading.

it's funny, my 99 Mustang GT's analog speedometer was exactly 1mph faster than the gps. the mustang's digital speedometer exactly matched the gps (even down to the tenth of a mph).

OverLOAD

The speedometer, and the tach, are a little bit off. If you think 2% is bad, I had a '96 MX-3 that read about 10% higher than how fast I was really going.

IF you don't like it, make sure you buy slightly larger tires when you replace them. Just don't forget that you're going faster than it says.

Regards,

OverLOAD

BruceInColorado

I used to switch out the tires and wheels when I restored classic Mustangs. The speedometer was always "off" as a result, so I would have to experiment with different speedo gears. I doubt we can do that with the RX-8, so make sure you do some math to make sure what your actual variation is going to be. (Either that, or get tires exactly the right size to account for the percentage difference in the speed: i.e., if your speed is 2% off, then you'd want to get 2% bigger or smaller tires. ) Since we're dealing with round shapes here, it isn't as simple as 2%, obviously... so there must be a formula out there for quickly figuring it out. Anybody have a formula like that offhand?

OverLOAD

If you look on tire rack, they have # of revolutions per mile listed for most of the tires they sell. Get a tire that has 2% less revolutions than the stock tires. I belive that somewhere around 830 revs/mile is what the stock tires do. If you get one that has about 810 to 815 rotations per mile, it should be a lot closer.

Also, keep in mind that as you run the rubber down, it will take more rotations of the wheel to maintain the previous speed, as the circumference has been reduced as a result of the radius being worn down, as the tread wears down.

Regards,

OverLOAD

Gord96BRG

The math is pretty basic, but the Miata.net Tire Size Calculator does it all for you. Enter the original size, enter the new size, and it will give you all the different specs, as well as the speedometer change.

Regards,
Gordon