Car revs strangely, but not a clutch issue?
 

I have searched high and low for exactly my issue, but I have not been able to find an answer to this.

In all gears except for first, my car's revs jump when I put my foot down for about half a second, and then the revs return to normal and my car accelerates normally. The rev spike seems proportional to how sharply I depress the throttle, but is not effected by hills. During the rev spike my car still accelerates.

I assumed that I needed a new clutch, so I bought one and took the car to a mechanic. He drove the car and said that the car did not need a clutch because it was still accelerating hard. He said that different cars act differently and did not make any recommendations. I am beyond confused because I know that this is not normal for a G35. I continued to drive the car for about six months ignoring the issue (about 5,000 miles mostly city) and the issue has not become any worse.

There is no smell of clutch and the issue is nothing more than a mild annoyance as it essentially feels like poor throttle response.

If there is another thread covering this issue, kindly direct me to it. Thanks in advance for your help guys.

-Ben

Wrong, you have a slipping clutch, that's EXACTLY what it starts to do when the clutch begins to slip.

If you get out on a steeper hill, put it in 6th gear, floor it, the revs will spike more (no advantage of gear reduction in your highest gear) and you should be able to smoke the clutch pretty easily. Then you can limp it back to the mechanic and tell him he's wrong.

Personally I would find another mechanic since it sounds like he's full of **** and doesn't even know what a slipping clutch is like when they first start to go out.

There's also a good chance that it's actually a failed rear main seal that has contaminated the clutch with a little oil that's causing the slipping. But not enough oil to be dripping out onto the ground.