I've got 3.92's and I've got the RPM's beat all around...something is different about this car, or something is wrong, or we dont' have the whole story.

Either the car is not hitting it's last gear, or it's being held there for some reason, or it has smaller tires - which would affect the speedo.

Take it to the dealer and have it checked out. Make sure they know that everyone else you talk to with these cars are hundreds of RPM's lower than you are at the same speed....move on...

X owners who contemplate changing gear ratios should remember that the front diff must repeat must be the same ratio as the rear diff.

In my case, on a run from Winnemucca, Nevada to Boise, Idaho, mostly running at night, when my car had just broken in, with about 2,500 miles on it.

Was interesting to find that it's governed to 92 MPH - had a few stretches where I wanted to run 100 with cruise engaged but the "accelerate" feature just died at 92 MPH (like a rev limiter). Then, when I manually accelerated to 100 and tried to re-engage cruise, it wouldn't engage until it had slowed to 92 mph. Being a lazy guy - I just left the cruise on.

Seriously, I tapped the brakes and slowed to 75 MPH or less (as situation warrants) whenever I encountered another car, which was probably 10 times in 300 miles. The "G" is a high performance sedan, and I'd bet that the ones they sell in Germany run 140 on the autobahn for long stretches at a time (probably without cruise control though, eh?).

Also I have regularly run 90 MPH+/- for long periods on Interstate 5 in the remote agricultural Central Valley and in the far northern California stretches (Redding, etc.) - and on a couple of cross country runs, too (say SF, California to Dallas , Texas). Always little or no traffic, usually 11:00 PM - 5:00 AM times, wide, flat Interstates with big shoulders/medians and runoff areas, etc. - again, as the situation warrants. I'm a fast driver - I'll grant you, but not an unsafe one (that's my story, and I'm stickin' to it!).

Pity the City Dweller with a "G", for he knows not what he has !!

3100 R's @ 80

I had put this together a little while ago when my son was fooling around with changing his wheel and tire setup for his 300ZX. I adapted it for my 2004 G35X. One can put in various gear ratios, tire and wheel sizes and see what the effect on MPH and speedometer error would be. You can also input a speed and see what the RPM would be in each gear. You'll notice I have set 80MPH since that is the speed everyone seems concerned about.

It's attached to this post as a PDF of the spreadsheet. If anyone thinks it may be useful and wants the actual spreadsheet, let me know.

Oh yeah, mine runs right between 3000 and 3100 RPM at 80 MPH indicated. (Indicated being what the speedo displays, I've never checked the speedo readings over a measured mile.)

Maybe his complaint is when he's giving the car a little gas on the highway and the torque converter unlocks in 5th and the rpms will shoot up another 300rpms or so?