i just bought a 2007 m35x and noticed that when the car reaches its 5th and final gear, it then sounds like it needs to shift another gear because it sounds like a lot of back-pressure. It sounds like when you're driving a manual car and are in a gear which needs to be shifted up. Is this normal for the car to sound that way since it's a luxury sports sedan?

Sadly, it's made that way. I think our G revs way too high on the interstate... it has always felt like it needs a 6th gear at speed. It runs around 3K at 80 MPH I think...

Heath

that sucks...i wonder if there is something that can be done to change the length of the gears...

I suspect that changing the differential gearing would be easier, although it would kill your low end torque. You sort of get used to it after a while. The only justification I can think of is that they were trying to keep the engine in a "sweet spot" for emissions. I'd be curious to see how much better highway MPG would be with a taller top gear.

The '10 G has a 7 speed A/T... must shift more than it runs!

Heath

Easy to calculate as over the typical range: displacement x rpm.
Remember that each injector squirt is maintained at 14.7 A/F so at a constant speed, 10% gearing change will result in 10% fuel change PER UNIT OF TIME.

A 10% decrease in rpm from gear change will net out < 2.5% acceleration change. Acceleration a cube root of torque.