I've driven several cars, including my current one, where the dash was 2-3 mph faster than the GPS. I kind of got the impression that they do that on purpose from the factory so people think they're driving faster than they are. No idea if that's true or not. I also don't know how accurate the GPS is.

 

^ Most of the cars I've driven are like that. My last Trans-Am was the closest and it was still 1-2 off. My Mom's Suburban is about 5MPH slow.
But my G is completely dead on at 80. Confirmed by my cell phone's GPS, my Dad's Garmin, and a couple of Radar 'your speed is' signs. But the crazy part is even though the needle on the dash is dead on perfect, it's not really displaying what the car 'thinks' it is running. When the Dash says 80 and the GPS says 80 the car's ECM is showing 76 or 77, which is just strange to me. On my last car the ECM read the same speed as the dash. In my cousin's Bonneville he has the little HUD and it reads slightly less than 1mph off from the dash. Yet the G35 has 3-4MPH difference between the computer and dash?????
I will tell you this, while the G35 is perfect at 80, the speedometer becomes increasing inaccurate after that.

 

Who cares. . .
I drive by Tach only. . . .

 

tach is normally an avg of 200rmp off.

Its not any more accurate than the speedo.

 

Yeah, so whats your point?
No instrumentation is 100% accurate. All instrumentation has some level of error, even the most sophisticated.

Not to mention the human eye isn't going to perceive an error of 200RPM when accelerating your car towards redline anyways.

 

Here’s the point genius:

The thread is regarding what rpm your car is at 80mph (has nothing to do with redline)…

You absolutely can “see” the difference in 200rmp – if your tach is sitting at 3K for example and the ECU is registering 3200 – or 2800.
As it pertains to your post – the post you responded to mentions the speedo not being accurate; you said “Who cares. . . I drive by Tach only. . . .” any logical thinking person would conclude that you meant the speedo’s inaccuracy isn’t important because you drive by tach (implying it is accurate).

If the fact that you drive by tach does not imply it is more accurate – then your own question about “what’s your point” should be asked to this post: https://g35driver.com/forums/4747686-post48.html

Your responses when you debate me are always pointless – just like your inane squabble in this thread: https://g35driver.com/forums/engine-...ance-chip.html... you aren't nearly as bright as you think you are... please be better prepared when you respond to me from now on.

 

Can't disagree with you there. You definitely know your stuff . . . especially when it comes to potato chips.

 

Getting this technical (or childish) would mean you guys need to run a GPS and datalog via a Cipher or something.

Please continue the purse fight

 

2003.5 6mt sedan 275/30/20
4.083 fd = 3,450 @ 80mph

 

or dyno... Cipher and dyno is what I am referencing...

 

thanks for the info, updated

how do you like the 4.08? Seems like it would change the car altogether.

 

Just to clear things up.

03-06 RWD 5AT Sedan (open or VLSD) - 3.3 gear
03-07 RWD 5AT coupe (VLSD) - 3.3 gear
04-06 AWD (open) - 3.5 gear
All 6MTs (open or VSLD) - 3.5 gear

Minor differences in RWD 5AT rpms in 5th at 80mph can be attributed to the following:

1) Worn tires (ie shorter)
2) Shorter tires than stock
3) Taller tires than stock
4) Torque converter locked
5) Torque converter unlocked
6) Torque converter in slip-lock

 

or the obvious - shorter FD was installed.

 

not entirely true...06-07 5AT coupes have 3.5 FD

 

Speedometers are set to always display faster than actual.

http://www.caranddriver.com/features...andal!-feature